Respiratory Infections and Recovery in Horses

How long does it take for a horse to recover from a respiratory virus, such as equine influenza or herpesvirus (EHV)?

Respiratory Infections and Recovery in Horses

Q.  When a horse contracts a virus, such as equine herpesvirus (EHV) or influenza, how long does it take for him to recover and be ready to condition and compete again? How long should I wait before taking him to another horse show? I don’t want to put any other horses at risk.

A.  Respiratory viruses such as influenza and equine herpesvirus affect horses differently, with clinical signs ranging from a mild cough, nasal discharge, and fever to more severe and profound respiratory illness and high fever.

Some horses recover quickly, whereas other suffer prolonged illness or develop secondary disease and complications. A good general guideline is to provide at least one day of rest for every day of fever following resolution of clinical signs to allow the respiratory tract and immune system to recover. After this period, you can reintroduce the horse into work gradually.

Horses might continue to shed virus and be contagious for some time following resolution of respiratory illness. Thus, veterinarians recommend keeping an affected horse isolated for 28 days after signs resolve. Alternately, your veterinarian can perform diagnostic testing as early as 14 days after clinical signs resolve to potentially release the horse from isolation sooner.

About The Author


Jordan Kiviniemi-Moore, DVM, cVMA, of Rood & Riddle Equine Hospital, grew up in Lexington, Kentucky, pleasure riding and dreaming of becoming a veterinarian. In 2010 she graduated from Transylvania University with a BA in Biology. She earned her veterinary degree from Auburn University College of Veterinary Medicine in 2014 and completed a rotating equine internship, which included internal medicine, surgery, and ambulatory rotations, at the University of Missouri College of Veterinary Medicine in 2015. Her areas of interest include theriogenology and primary care. In 2017 she earned her certification in equine acupuncture.


Santa Anita Racehorse Breakdowns: Thinking Beyond the Track Surface

Aside from footing, a number of factors could be contributing to catastrophic injuries. What would it take to definitively pinpoint a cause? Dr. Peta Lee Hitchens, who has an interest in the epidemiology of racehorse breakdowns, explains.

Santa Anita Racehorse Breakdowns

Twenty-two Thoroughbred racehorses have died or been euthanized at Santa Anita Park, in Arcadia, California, during its current race meet due to injuries sustained while racing and training. The Stronach Group, which owns the track, has closed the venue to both live racing and training multiple times, most recently on March 14 after the 22nd fatality. The Stronach Group has also established a variety of initiatives for racing and training at the track and plans to reopen on March 29.

So far investigation has reportedly been largely aimed at the track surface, with repeated checks finding that the footing is consistent. We at The Horse wanted to give the reader a look at this issue through a different lens: epidemiology, which the Centers for Disease Control defines as a “method used to find the causes of health outcomes and disease in populations … (where) the patient is the community and individuals are viewed collectively.”

If we were to look beyond the racetrack surface, what would it take to definitively pinpoint a cause? We spoke with Peta Lee Hitchens, PhD, a research fellow in the University of Melbourne’s Equine Orthopaedic Research Group, in Victoria, Australia, led by Professor Chris Whitton (BVSc, PhD, FACVSc), with an interest in the epidemiology of racehorse breakdowns. Hitchens isn’t involved in the Santa Anita investigation but is able to offer insight into how epidemiologists approach racetrack breakdowns.

A veterinarian and epidemiologist analyzes racing injury data collected by The Jockey Club’s Equine Injury Database; information on all horses at participating tracks that die or are euthanized as a direct result of injuries sustained participating in a race and within 72 hours of such a race (including musculoskeletal injuries, nonmusculoskeletal injuries, and sudden deaths) are entered in this database. Training and nonracing fatalities are also collected at participating tracks but not included in EID’s annual statistics. For the layperson, what is an epidemiologist?

Hitchens: Essentially, a detective! An epidemiologist investigates the reasons for injury or disease occurring within populations. They are most popularly associated with investigating disease outbreaks. But as an equine veterinary epidemiologist I focus on investigating risk factors for injuries and fatalities in racehorses with the mantra that “prevention is better than a cure.” Tell us about your specific interests as an epidemiologist. Why did you become interested in these topics?

Hitchens: I’ve always loved data and find a particular satisfaction in using it to solve problems. I had just completed a master’s degree in veterinary epidemiology when in 2005, Ray Silburn, the jockey that rode my first horse to his first win, was in a race fall that resulted in him becoming paraplegic. In that same year there were two jockey deaths in Australia. Because of my involvement in the industry, as a breeder and owner of a racehorse, and later as a steward and operations manager, I felt that safety in the industry could be improved. From there I proposed a PhD project to investigate the cause of falls, injuries, and fatalities to jockeys in Australia. The link between racehorse and jockey injury became apparent during my postdoctoral studies at the University of California, Davis, under Professor Sue Stover (DVM, PhD, Dipl. ACVS). What does an epidemiologist consider, categorically, when he or she is asked to assess a situation such as the series of breakdowns at a racetrack?

Hitchens: The most important resource for an epidemiologist is good-quality data, preferably large amounts of it (big data!). I recently completed a meta-analysis (a statistical technique for combining data from multiple studies) that identified commonly reported factors that increase a horse’s likelihood of sustaining a fatal injury.

In our study we found that almost 300 potential risk factors have previously been investigated. Factors most frequently reported with consistent evidence of increasing risk were the following:

Santa Anita Racehorse Breakdowns
  • Horse characteristics such as:
    • Older horse age,
    • Age at first start,
    • Male sex (particularly entires [aka colts, stallions]), and
    • Higher race class or lower claiming price;
  • Race characteristics such as:
    • Firmer track conditions on turf and sloppier conditions on dirt,
    • Longer race distance, and
    • A greater number of horses starting in the race (in other words, larger field size).

Management-related factors including issues identified at prerace examination, previous injury, and recent administration of medication or injections.

Also, exercise history was found to be key:

  • More time since their previous start,
  • Greater number of starts, and
  • Longer career length.

But conflictingly, risk factors related to recent exercise history pointed to at least two mechanisms of injury:

  • Horses with well-adapted bone may sustain a fatal injury as a result of accumulated bone damage following a period of intense high-speed training, and
  • Horses with poorly adapted bone that are training at relatively low levels of intensity or coming back from a layup and are then introduced to high-speed exercise too rapidly were also at increased risk of sustaining a fatal injury.

Having access to information about the horse, including veterinary, training, and racing history is critical in being able to:

  • Determine which factors increased risk of injury; and
  • Identify those horses that might be at risk in the future. Beyond the track surface itself, what are the types of things you’d consider?

Hitchens: Track surface and its condition is just one factor. It is unlikely that it is just one cause for these fatalities occurring; that is, I think the reasons are multifactorial—a series of conditions that coincide to create a spike in fatalities. I would consider recent increases in training or racing intensity, whether the horse has come back from a rest (be it long or short layup), medication administration, and recent lameness history, among other things, as already mentioned. And I would consider these in unison, because these factors can all interact with each other to exacerbate the risk of injury or fatality. What would it take to realistically assess things that have been proposed by the public as causes, such as extracorporeal shock wave therapy and furosemide (also known as Salix or Lasix) or other drugs?

Hitchens: Good veterinary records of any medications or veterinary treatments are required. I honestly think their disclosure should be mandatory, for all racehorses, not just those that sustain a fatal injury. Because, in order to understand risk of racehorse injury, we must compare the frequency and types of veterinary treatment in injured horses (cases) to horses that have not been injured (controls). The way we compare the cases with controls is by generating regression models using the data collected for each horse. These models essentially assess how successfully a variable (potential risk factor such as a veterinary treatment) does its job in predicting whether a horse sustains an injury.

Unfortunately, all epidemiological models generated to date have only been able to achieve about 65% predictability, where 100% perfectly predicts a fatal injury and 50% being no better than chance or flipping a coin. With such inadequate predictive capability, there is still more to be done to refine these epidemiological models. Better data, specifically training and veterinary data, is likely the key to improving the predictability of these models. What would the steps be if the investigation seemed to always stop in one place inconclusively?

Hitchens: These injuries are generally multifactorial. For example, Professor Tim Parkin (BSc, BVSc, PhD, DECVPH, MRCVS, of the University of Glasgow) has previously identified risk factors for fatal injury in North America, as well as specific risk factors as part of the investigation of equine fatalities at Aqueduct (Racetrack, near New York City) during the 2011-2012 fall/winter race meet. Thirteen of the 21 horses were found to have six or more risk factors present.

Risk factors for racehorse fatality specific to the New York task force analysis included:

  • Starts made by entire males (colts, stallions, ridglings/cryptorchids) compared to geldings, fillies, or mares;
  • Horses in claiming races compared to those in nonclaiming races;
  • Starts made at Aqueduct compared to Belmont or Saratoga (two other New York Racing Association [NYRA] Thoroughbred tracks); and
  • Starts made on Aqueduct’s inner dirt track compared to all other NYRA tracks.

What contributed to the spike was that in the 2011-2012 season there were more starts made by entire males and more starts at Aqueduct, followed by Belmont, by horses in claiming races and with a claiming price, compared to Saratoga.

Investigations that are inconclusive usually occur because there is a lack of data, or access to the right data, in which to find the cause. We just need to be more vigilant in the future about collecting and maintaining this data so that analyses can be conducted quickly and efficiently—data supplied in real-time is the goal. Do epidemiologists generally work alone or in a team and why?

Hitchens: A team, for sure! The University of Melbourne’s Equine Orthopaedic Research Group consists of me (an epidemiologist), engineers, pathologists, veterinarians, and more. Although I love to analyse data in my own little world, most of it comes from other sources (e.g., mechanical engineers conducting bone-loading experiments; or pathologists measuring the degree of damage in bone). As a team, all our respective knowledge is also needed to interpret the findings from such epidemiological studies. What could the implications of the situation at Santa Anita be, looking at it from an epidemiological perspective (or not looking at it that way)?

Hitchens: I don’t think there is any question that this needs to be looked at from an epidemiological perspective. It is crucial.

By looking at the Santa Anita situation in this way we’re more likely to identify risk factors which can direct further investigation, avoiding spending time and energy on factors that have no influence on injury. How long does it take for these types of studies to be conducted?

Hitchens: This is dependent on the availability and quality of the data. If everything is “ready to go,” in as little as a month, but in my experience records could be paper-based, requiring collation, and databases may require significant cleaning—in these cases, potentially three months or more. With clean accessible data, the analysis in itself is quite quick! I understand you’re one of the only people in the world who takes the risk to riders to be a central part of the discussion. Tell me a little about this. Why isn’t it considered so much as horse safety?

Hitchens: In a collaborative study with UC Davis and the California Horse Racing Board, we identified racehorse fatality as the most common reason for a jockey fall. About two-thirds of such falls resulted in substantive injury to the jockey. This is likely because when a horse breaks down or collapses, the jockey falls with the horse and additionally poses a threat to following horses and their riders. Jockey falls most frequently occurred due to Thoroughbred fetlock injuries, as well as with axial (e.g., spine, pelvis), bilateral (occurring in both front or both hind limbs), and multiple injuries. Focussing on the prevention of the most common fatal injuries in racehorses should go some way to decreasing rates of falls, injuries, and fatalities to jockeys.

I believe the main reason this linkage wasn’t explored previously is because different research groups were involved in analysing the two sets of data—that is, medical researchers in conjunction with medical racing officials analysed data relating to jockey falls and injuries and other health issues, and veterinary researchers analysed risks related to the racehorse. Given we are essentially working with similar underlying racing data, that there are shared risk factors, and that any interventions would affect the risk to both the horse and its rider, it is logical that the analyses be conducted in conjunction. Does artificial intelligence (AI) have any role at this point in the epidemiological study of catastrophic racehorse injury and, if not, what is its potential for this application?

Hitchens: The beginnings of the use of AI have been explored using machine learning techniques by Georgopolous (PhD thesis, 2017). This study found that the predictive power of a machine learning methods versus standard regression techniques used in epidemiological studies was similar. Really, I think this is because the results from different forms of modelling are only as powerful as the data we put in. If we can improve our data collection and collation methods AI will certainly be interesting to pursue. What’s next in this field to make useful strides with racing industry research?

Hitchens: Epidemiology as it stands does have its limitations. We need to find more creative means of identifying the causes of injury, including understanding how such injuries develop at the bone biology level. This means focusing our research on factors that influence the interaction between adaptation, accumulation of damage, and repair of bone. We can piece together our knowledge about each facet of the bone biology process using mathematical models. Then, by combing mathematical models of bone biology processes with epidemiological models of risk factors, we will be able to target our interventions at the root cause.

About The Author


Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

Castration In The Horse

Becoming educated on the entire process of castrating horses can only help you make decisions that are best for your horse. Castration has been used to control masculine/aggressive behavior in the male horse for hundreds of years. In medieval

Becoming educated on the entire process of castrating horses can only help you make decisions that are best for your horse. Castration has been used to control masculine/aggressive behavior in the male horse for hundreds of years. In medieval times, kings rode stallions, and people of less stature often were described as riding geldings. Castration also is called gelding, cutting, or emasculating. The scientific name for castration is orchidectomy–orchid meaning testicle and -ectomy meaning to remove or resect. Orchidectomy therefore is the surgical removal of a testicle.

Castrating horses in the past was, of course, not always performed by licensed veterinarians. Even today in some cultures it is performed by a lay person. Although it is one of the most common surgeries performed by a veterinarian, it should never be considered routine, as the procedure can have very serious complications. Furthermore, the follow-up care is extremely important. In this article, we’ll see how an orchidectomy is performed in the horse, when it can be performed, potential complications, and the myths behind castration in horses.

Why Castration?

Castration in any species involves the removal of one or both testicles and associated structures (such as the epididymis) and part of the spermatic cord. The spermatic cord is the tube-like structure that contains the blood supply (veins and artery), ductus deferens, and nerve supply to the testicle. Castration usually is performed in male horses of inferior breeding stock, in cases of cryptorchidism (see “Cryptorchidectomy” in the September 1999 issue of The Horse, article #372), or in stallions which are difficult to manage. Some owners believe that stallions perform better than geldings; this is common in several disciplines.

The testicles are the organs responsible for producing testosterone (the main hormone that creates stallion-like physical features and behavior). Removal of both testicles usually rids the horse of unwanted stallion-like behavior, including screaming at and fighting with other horses, attempting to mount other horses, erection, masturbation, and potentially aggressive behavior toward humans. However, when castration is performed at a late age and/or after the horse has been used to breed mares, is not always successful in abolishing learned stallion-like behavior. Even though the horse will not be able to reproduce, the behavior of mounting mares in the pasture in an attempt to breed and aggressive behavior with other horses might not cease.

According to Christine Schweizer, DVM, Dipl. ACT, from Cornell University, the age of the horse at the time of castration usually plays a big factor in residual stallion-like behavior. Older stallions which have been in a breeding program are much more likely to retain studdish behavior than those gelded as yearlings. Castrating older stallions will tone down the stallion-like behavior, just not necessarily eliminate the behavior completely.

When To Castrate?

Horses can be castrated at any age. I have castrated foals at one day of age and stallions into their 20s. Although both of these extreme situations were emergencies where the horses had developed scrotal hernias (the small intestine had herniated or protruded into the scrotal sac), all recovered well. Most veterinarians will agree that castrating horses at a young age (less than one year old) is ideal. Male horses at that age have smaller testicles that are easier to remove and have less of a chance of severe bleeding post-operatively. Many people castrate horses when they become a management problem–around two to three years of age. This could be due to a desire for the horses to develop a more masculine appearance (thicker neck, heavier build).

If a horse is gelded earlier in life, then it will grow taller–closing of the growth plates in the legs is delayed with early castration. The ideal time to castrate a horse is variable and will depend on several factors, including the management of your farm, the climate, training schedules, and so on.

For example, you might want to wait to castrate your yearling colt until he is two years old. However, if the barn where you board your horse only has one paddock, turning your intact colt out with other horses invariably results in a fight when the colt begins mounting and herding the other horses. To save the peace (and injuries to your colt), it might be best to castrate him earlier.

Another example could be that you want to castrate your 2-year-old colt in January so that he is acting like a gelding by the first show in March. However, you live in central New York, where heavy snow and extremely cold temperatures are the norm in January. It might be best to wait for warmer weather so that regular exercise following castration won’t be impeded. Or, for a little more money, you can have him castrated at a clinic where the incisions are closed and there is no need to worry about the castration sites becoming swollen or infected. What’s the difference between field and clinic castration? Read on.

Field Vs. Clinic Castration

A castration can be performed in a number of different ways, and each veterinarian will have a different preference. The differences usually are due to several factors, including the farm’s facilities, how the farm is managed, age of the horse, and what lay-up time can be allowed following castration. Other important factors are whether the horse has both testicles descended into the scrotum, and the skill of the veterinarian performing the surgery.

The most basic requirement for a normal castration is that the horse has two testicles descended into the scrotum. Your veterinarian must confirm this before surgery is begun! If one or both testicles are “missing” (or more correctly described as not descended into the scrotum), then the horse is considered a cryptorchid. A cryptorchid castration requires more extensive surgery than a routine castration, so that surgery usually is not performed in the field.

Removing only the descended testicle and leaving the retained testicle is not an ethical procedure, due to the problems described previously. Furthermore, removing only one testicle will not cut stallion-like behavior in half–so don’t be fooled!

If the horse has two fully descended testicles, then the second decision to make is whether or not he will be anesthetized for castration. Castrations can be performed with the horse standing or recumbent (lying on his side or back) and under anesthesia.

The requirement for a standing castration is that the horse must be big enough for your veterinarian to lean under the belly to remove the testicles–no miniature horses! The horse must be trained well enough to be restrained properly–that means no standing castrations in foals. The reason standing castrations are performed is that some people do not want the horse injuring himself during administration of anesthesia or recovery, or having a reaction to the anesthetic drugs. These very seldom happen.

Standing castrations are much riskier to the veterinarian performing the procedure than to the horse; many veterinarians will not perform standing castrations due to the risk of injury to themselves. Before you decide how you want your horse castrated, you should weigh the pros and cons with your veterinarian. The main advantage of standing castrations is that the horse does not have to be anesthetized. The horse will have to be sedated and restrained with a twitch, but he will not have to lie down, therefore avoiding the possibility of harming himself when he attempts to stand after the procedure. The main disadvantage is that if a major problem occurs (severe bleeding or evisceration–removal of part of or a whole organ), then it is nearly impossible to correct with the horse standing, and the horse will have to be anesthetized very quickly for treatment.

Some people do not want to care for the incision sites, or wait for the open incision sites to heal. For those owners, the horse can undergo surgery in a clinic and have the incisions closed. Closing the castration incisions eliminates most of the complications of castration such as hemorrhage, infection, delayed healing, and intestinal herniation (more on these later). This procedure is, of course, more expensive than a routine castration in the field, but for some the saved time and peace of mind is very much worth the extra cost.

Normal Castration

When a horse is presented to me for castration, I talk to the owners and describe what is going to happen and what the owners/caretakers can expect afterward. I find this to be extremely important, as it never ceases to amaze me how someone who says they have experience with castrating horses is scared afterward by the open and draining castration sites. The first step is good communication.

The second step is a thorough physical examination of the horse, including palpation of the testicles. This is to make sure that both testicles are descended and that there is no evidence of a scrotal hernia (intestine that has herniated from the abdomen into the scrotum). If the horse is healthy and normal anatomically, then surgery can be performed at the farm. If there is a hernia or if a testicle is missing, then we must plan for the operation in a clinic instead.

The next step is to ensure that the horse has been vaccinated against tetanus in the last six months. A tetanus booster should be administered to any horse that is undergoing surgery, because the surgical sites can become infected with the organism that causes tetanus. Tetanus is easy to prevent, but very difficult to treat (and often is fatal). If there is a question of vaccination status, administer the booster vaccine!

I perform 99% of castrations with horses anesthetized, so this is the method I will describe.

After the horse is sedated, then anesthetized with drugs given intravenously, the horse is placed on its side with the hind legs tied out of the way. The scrotum is prepped for surgery and two incisions are made through the skin, one over each testicle. The connective tissue surrounding each testicle is removed, leaving the testicle, epididymis, and spermatic cord exposed. At this point, emasculators (instrument with a broad surface and a cutting edge made for castration) are used to crush the blood supply in the spermatic cord, then sever the vessels along with the other tissue. The emasculators are left in place for up to two minutes.

When the emasculators are removed, the stump of the spermatic cord (the part that is going to remain in the horse) is inspected for hemorrhage. This is repeated on the other side.

The last step is veterinary preference; I remove the skin between the two sites, leaving one large incision to drain. Other veterinarians leave the two sites open without removing the skin in between. The horse will stand up within 10-20 minutes, sometimes sooner. The open incisions are left to heal on their own (otherwise called second intention healing).


Although castration is one of the most common surgical procedures performed in the horse, it also has several complications, some of them quite serious. The most common complications are swelling at the incision sites or in the prepuce (sheath), and post-operative bleeding. It is normal for an occasional small amount of blood to drip from the incision sites; however, a steady drip or stream of blood is too much. If bleeding persists after surgery, then the incision must be packed with gauze to apply pressure and stop the bleeding. In cases of severe bleeding, the horse usually is anesthetized again and the offending blood vessel is ligated (tied) to prevent further hemorrhage.

It is normal and expected for a certain amount of swelling to be present at the castration site. However, severe swelling usually indicates a problem, usually infection.

Castration sites need to heal from the inside out. If the outside skin heals first, serum and blood can accumulate in a pocket and the site will become infected. Your veterinarian will treat the infection with antibiotics, and probably will reopen the incision sites for drainage. Sometimes the infection ascends the remaining spermatic cord and surgery needs to be performed to remove the infected tissue. Once this is done, the problem is solved. The incision is once again left open to drain.

One of the most serious complications is eventration. This is when a segment of small intestine travels from the abdomen down through the inguinal canal (a small opening that connects the abdomen to the scrotum). In an uncastrated male, this would be called a scrotal hernia. However, in a castrated horse with open castration sites, the intestine can descend through the open incisions and disaster can result.

This is a life-threatening emergency–the first sign of intestine (or anything else) protruding from the castration site should alert you to call the veterinarian immediately. Emergency surgery must be per-formed to return the intestine to the abdomen and close the opening to the inguinal canal.

The horse’s omentum, which is a fatty yellow tissue that surrounds some of the abdominal organs, also can protrude through the open incisions. This is called omental eventration. If this happens, the offending omentum will be removed via an emasculator, but this is not life-threatening like intestinal eventration because the omentum will block the inguinal canal and prevent the intestine from coming through.

Follow-Up Care

Care after the surgery is extremely important, especially if the skin incisions are left open to heal on their own. The horse should rest quietly in his stall for 24 hours following castration. After that time, however, it is imperative that he has exercise for at least one hour every day. Frequently, people make the mistake of turning the horse out in a paddock or pasture. Many times the horse, especially if he is a little sore, will just stand quietly and graze. Castrated horses need exercise to keep their incisions draining appropriately. Therefore, they need to be longed or chased!

If they are not exercised appropriately, then the skin incisions can close prematurely, and the area can become very swollen, painful, and infected. Daily cold water hosing also helps keep the swelling down and will help clean the incisions.

In most horses, the effects of the residual testosterone in the horse’s body will last approximately six weeks. So unfortunately, you will not see an immediate attitude adjustment in unruly horses. For this reason, I recommend not turning out your new gelding with mares or any other horses until six weeks after castration. He can’t impregnate your mare during that time, but he might get hurt when he mounts her uninvited.

The “Proud-Cut” Myth

Geldings which continue to mount mares or those which have continued aggressive behavior following castration are often referred to as being “proud cut.” This term has been used to imply that the castration was not completely performed (intentionally or unintentionally), and that a portion of a testicle or epididymis was left in the horse and is still producing hormones (particularly testosterone) that cause stallion-like behavior. If a portion of the epididymis was left in the horse, it would not cause the horse to continually act like a stallion as the epididymis cannot produce testosterone on its own.

If you have a “gelding” which acts like a stallion, there are two possibilities.


Problem 1: The horse might have a cryptorchid testicle that is retained high in the flank or in the abdomen that still is producing testosterone and creating the stallion-like behavior. The testicle was not found during a normal castration, and the entire testicle or a major portion of it was left in the horse.


Solution: Your veterinarian can take blood samples to determine if your horse is producing testosterone at similar levels to a stallion. A baseline blood sample is taken, then a hormone (hCG–human chorionic gonadotropin) is administered and will stimulate testosterone production if the horse has functional testicular tissue in his body. This is one of the best ways to determine if a horse has a cryptorchid testicle hidden somewhere.

Problem 2:
Your horse is a true gelding with no testosterone-producing tissue in his body (i.e., no testicular tissue) and still displays stallion-like behavior, possibly due to learned behavior. On the other hand, in one study in which male horses’ behavior was evaluated following castration, there was no significant difference in behavior whether the horses were castrated at less than two years of age or at more than three years of age. Regardless of the age at which they were castrated, up to 30% of the horses still displayed stallion-like behavior, including aggression toward other horses. The study noted that 5% of the horses displayed aggression toward humans.


Solution: Most veterinarians believe that in true geldings, appropriate training can reduce or eliminate the stallion-like behavior. Luckily, most castrations in horses are performed with no complications, and a healthy, well-adjusted gelding is the end result.


Biomarker Could Help Determine if Your Horse Needs Colic Surgery

Measuring the biomarker creatine kinase in abdominal fluid can help distinguish horses with ischemic (lacking blood flow) intestine due to a strangulating lesion—and, thus, require surgery—from those without.

colic surgery
If a horse needs colic surgery, the sooner he gets to the operating room, the better. But, in the early stages of diagnostics, it can be challenging for veterinarians to determine whether a colicking horse could recover with medical management, or if he has an issue—such as a strangulating lesion—that must be corrected surgically.Fortunately, researchers are helping make the decision more straightforward to expedite the process. At the 2018 American Association of Equine Practitioners Convention, held Dec. 1-5 in San Francisco, California, Isabelle Kilcoyne, MVB, Dipl. ACVS, suggested measuring a biomarker—the enzyme creatine kinase (CK)—in peritoneal (abdominal) fluid to help distinguish horses with ischemic (lacking blood flow) intestine due to a strangulating lesion from those without.

Veterinarians frequently collect and analyze peritoneal fluid during work-ups of colicky horses, said Kilcoyne, an assistant professor at the University of California, Davis, School of Veterinary Medicine. In a study in rabbits, researchers determined that peritoneal CK levels increased significantly within an hour after ischemic injury. And, veterinarians know that horses with elevated blood plasma CK levels are less likely to survive surgery than those with plasma CK levels under 470 IU/L, based on a study out of Colorado State University.

Kilcoyne and colleagues sought to find out if CK could be a useful marker of intestinal ischemia and, therefore, an indicator a horse needs surgery.

The researchers gathered information from colic cases arriving to their clinic. At admission they collected blood and peritoneal fluid samples from:

  • 21 horses ultimately diagnosed with strangulating intestinal lesions;
  • 40 ultimately diagnosed with colic but not strangulating lesions; and
  • 10 healthy controls.

They found that control horses had plasma levels of 165 IU/L and peritoneal fluid CK levels of 6 IU/L; horses without strangulating lesions had plasma CK levels of 271 IU/L and peritoneal levels of 6 IU/L. Meanwhile, horses with strangulating obstructions had significantly higher values: plasma CK values were 1,181 IU/L and peritoneal 185 IU/L.

Kilcoyne said peritoneal CK levels are more likely to correctly identify horses with strangulating obstructions (sensitivity of 95.5% and specificity of 82.1%, with a cutoff of 16 IU/L) than peritoneal fluid lactate levels (sensitivity of 81.8%, specificity of 92.1% at a 3.7 mmol/L cutoff)—another biomarker vets frequently use to predict ischemia in colic patients. However, CK poses a slightly higher risk of yielding false positives than lactate, she added.

She suggested veterinarians measure both peritoneal CK and lactate levels in colicking horses, always factoring in the horse’s clinical signs when interpreting the findings. She added that the development of a stall-side CK test could expedite diagnosis in both field and hospital settings.

About The Author


Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.


Should My Horse Exercise on an Empty Stomach?

Riding before your horse gets fed could put him at risk for gastric ulcers. Find out why.

should my horse exercise on an empty stomach

Q.I board my horse and ride in the morning and sometimes late afternoon, often before he gets fed. I am worried about the potential gastric ulcer risk of riding him on an empty stomach. Is there anything I can do to combat this?

—Via e-mail

A.You’re right to be concerned. Although historically it wasn’t the case, veterinarians now generally understand that horses should have some amount of food in their stomach, ideally, at all times.

How Food Protects the Stomach

In horses’ natural setting, where they eat almost constantly and consume large amounts of forage, a fibrous “mat” develops in their stomachs, floating on top of the stomach acid. This mat helps prevent acid (which is constantly secreted in the stomach’s lower glandular portion, which is protected by a mucus layer) from splashing up and the nonglandular part of the stomach (where the cells of the lining do not produce protective mucus).

When we meal feed horses, this mat is diminished and, therefore, less of a barrier between the stomach acid and the unprotected nonglandular tissue forms. And, not surprisingly, most gastric ulcers are located in the nonglandular portion or along the dividing line (called the margo plicatus) between the two sections.

After your horse has finished eating, it takes only about 6 hours for the majority of that meal to leave the stomach. So, when you ride before meal times and many hours after the horse’s last meal, his stomach lacks the same level of protection that would have existed shortly after he ate.

Additionally, some foods can act as a buffer, helping to raise the pH of the stomach acid. This is especially true of forages, particularly high-calcium legumes such as alfalfa.

Finally, chewing causes saliva to be released, which also helps buffer the stomach acid. So, if your horse eats close to riding, his stomach acid might be less acidic due to this buffering action.

Preventing Ulcers

The best thing you can do when your horse hasn’t eaten for several hours before a ride is to feed something beforehand. This might just mean allowing your horse to munch on hay in a net while you’re grooming or feeding a pound or so of hay pellets. A legume hay or hay pellet such as alfalfa will help more than a grass hay due to the higher calcium levels and, thus, better buffering capacity.

Buffering and coating supplements are also available that have been shown to help either protect the stomach lining or buffer stomach acid. These supplements tend to be somewhat short-lived, meaning their beneficial action only lasts a couple of hours. But this would be fine in a situation where you’re just wanting that buffering protection for the duration of your ride. Some are more effective than others, so do your homework and see whether the manufacturers have any data to prove that their product does effectively buffer stomach acid and for how long.

About The Author


Clair Thunes, PhD, is an equine nutritionist who owns Summit Equine Nutrition, based in Gilbert, Arizona. She works as a consultant with owners/trainers and veterinarians across the United States and globally to take the guesswork out of feeding horses and provides services to select companies. As a nutritionist she works with all equids, from WEG competitors to Miniature donkeys and everything in between. Born in England, she earned her undergraduate degree at Edinburgh University, in Scotland, and her master’s and doctorate in nutrition at the University of California, Davis. Growing up, she competed in a wide array of disciplines and was an active member of the U.K. Pony Club. Today, she serves as the district commissioner for the Salt River Pony Club.

What Nutrients Does a Horse Need?

Any good feeding program meets the nutrient needs for the animal, maintains a healthy digestive system, and offers feeds of the highest quality. Does your horse’s diet include the required nutrients?

what nutrients does a horse need
With respect to weight management, balancing a horse’s diet while meeting its digestible energy requirements is extremely important. However, a horse requires other nutrients that should be considered when looking at the overall feeding program. Any good feeding program will be based on the following principles: Meets the nutrient needs for the animal, maintains a healthy digestive system, offers feeds of the highest quality. So, what nutrients does a horse need in his diet?There are several nutrients a horse requires such as water, protein, vitamins, and minerals. Specific amounts for each of these nutrients will depend largely on your horse’s weight and activity level or physiologic status (such as if an animal is growing or lactating). Detailed values of these requirements are found in the National Research Council’s Nutrient Requirements of Horses, and are summarized in the table below:

Nutrient Requirements of Horses at Maintenance


Water is by far the most important nutrient, and is most often overlooked. All horses should have access to fresh, clean water at all times. Without it, colic, dehydration, and even death could result. Horses’ water requirements depend greatly on their physiologic state—as a lactating horse will require significantly more water than a horse at “maintenance.” In general, a 500 kg horse will drink approximately 30-45 liters per day. However, how much horses actually drink will largely depend on diet; for example, a horse at pasture likely won’t drink as much as a horse eating hay because the pastured horse takes in water with each blade of grass.


Protein’s main function as a nutrient is to provide the building blocks for tissues, muscle, hormones, and enzymes. With respect to equine diets, we often classify protein requirements based on quantity and quality. Quantity refers to grams of protein required in the diet. Most horse owners think in terms of percentage of protein in a given feed, but how much the horse actually gets would depend on how much of that feed it gets. (Example: Feeding 5 kg of a 10% protein diet would give a horse 500 grams of protein [5,000 grams x 0.10]; feeding 2.5 kg of a 20% protein diet would also give a horse 500 grams of protein [2,500 grams x 0.20 = 500 grams].)

Horse owners should consider the total grams of protein intake per day, not the percentage. In addition to being aware of the quantity of protein a horse is getting, being aware of the quality of the protein is equally important. Protein quality refers to the amino acid make up of a feed. Some amino acids can actually be made by the body and are not essential from a dietary standpoint. Amino acids that cannot be produced by the body, such as lysine, are considered essential and must be provided for in the diet.

A high-quality protein should provide these essential amino acids. Good-quality sources of protein include the seed meals (such as soybean meal or linseed/flaxseed meal) and legume (alfalfa, clover, etc.) hays. The essential amino acid lysine is of particular importance because of its requirements for growth. Some equine feeds are relatively low in one or more of the key amino acids, with lysine being considered the first limiting amino acid (meaning that if insufficient quantities of lysine are present, the body's protein synthesis abilities are limited ). Thus, if a horse were easily meeting its protein quantity requirements but wasn’t getting enough lysine, the diet wouldn’t be suitable.

Let’s use this analogy: If amino acids were letters, and protein a word (a chain of letters), lysine could be thought of as the letter “E”; it is very important for the formation of many words and certainly important in writing a sentence or paragraph.

Fats and Carbohydrates

The main nutritional property of fats and carbohydrates is their ability to generate energy through being metabolized. However, specific types of carbohydrates and fats serve additional important functions for the horse. For example, complex carbohydrates such as fiber are extremely important for digestive tract health; the microbial ecosystem is highly sensitive to an insufficiency of fiber.

Furthermore, in humans it is now recognized that some types of fats are essential parts of the diet; namely the omega fatty acid group, including , omega-3 and omega-6. These fats are important for their anti-inflammatory properties and their roles in immune function. Horses also likely benefit from these omega fatty acids and research is ongoing, though these fats are not considered essential nutrients.


Equines require several minerals to meet a variety of functional needs, including skeletal integrity and cellular communication. The macro minerals (those needed in relatively high amounts) include calcium, phosphorus, sodium, potassium, chloride, magnesium, and sulfur.

Trace minerals (those needed in relatively small amounts) include cobalt, copper, zinc, selenium, iron, iodine, etc. Horse feeds tend to be variable in many minerals, and as they are usually low in sodium and chloride (salt), it is recommended all horses be offered some kind of salt source, such as a salt block.

Another important point about minerals is the significance of several ratios among these minerals, as the amount of one mineral in the diet may affect the use of another. For example, there should always be more calcium in the diet than phosphorus, ideally in the ratio of approximately 2:1. If this ratio is imbalanced, the horse may not be able to use the calcium in its diet and may develop bone problems.

The only way to know how many minerals are present in your feeds (particularly hay and/or pasture) is to have them analyzed at a local agriculture lab. Most commercially available feeds will have minerals added in quantities to meet the needs of the type of horse the feed is designed for.


Vitamins are classified as water-soluble or fat-soluble. The fat-soluble vitamins (they can dissolve in fat) include A, D, E, and K while the water-soluble vitamins include the B complex (niacin, thiamin, etc.) and vitamin C. The horse is unique with respect to some of its vitamin requirements in that the microbes located within the large intestine have the ability to synthesize the B complex vitamins and vitamin K. The microbes do so in quantities sufficient to meet most horses’ needs such that deficiencies of these vitamins are very rare and even difficult to induce experimentally.

Horses, unlike humans (and fruit bats, primates, or guinea pigs), can synthesize their own vitamin C and therefore generally do not require it in their diet. Vitamin D, synthesized upon the skin’s exposure to sunlight, is found in good amounts in sun-cured forages. Therefore, providing you feed good-quality hay (i.e., not last year’s batch) and your horse gets some outdoor exposure, it should be getting plenty of vitamin D.

Vitamins A and E are found in variable amounts in pasture and hay, with higher amounts found in pasture during the spring months and in hay that hasn’t been stored for too long. Most of the fat-soluble vitamins will degrade over time in stored hay.

Survey Results Establish Equine Research Priorities

Veterinarians and horse owners alike consider colic the most important equine health care problem in need of more answers.

Veterinarians and horse owners alike consider colic (gastrointestinal diseases) the most important equine health care problem in need of more answers, according to the results of research surveys conducted in partnership by the American Association of Equine Practitioners (AAEP) Foundation and the American Horse Council (AHC) Foundation.In 2018, AAEP and AHC asked members to complete similar surveys to identify the most pressing disease problems they encounter and to prioritize the importance of specific diseases. Following colic, veterinarians listed lameness, laminitis, osteoarthritis, endometritis, dental issues, lacerations, metabolic conditions, infertility, and pituitary pars intermedia dysfunction (PPID) as the 10 most common equine medical problems treated in their practices. These results resembled those of the AAEP’s 2009 membership survey, which identified laminitis, colic, arthritis, tendon injuries, and navicular disease as the diseases in most need of research.

When asked to rank technical areas in need of research, veterinarians listed horse-side tests, regenerative medicine, podiatry, exercise physiology, vaccines, and imaging as the top six.

Among horse owners, infectious diseases and musculoskeletal diseases followed colic/gastrointestinal/liver issues as their most pressing equine health care issues. Owners also prioritized research on pain recognition; information on genetic diseases; and research on nonmedical problems, including horse abuse/neglect, wild horse and burro management, alternative therapies, and the benefits of riding.

Owner survey results corroborated studies by the USDA’s National Animal Health Monitoring System on horse operations in the United States in 2005 and 2015. Injury (trauma/wounds), lameness, and colic were the most common problems occurring at horse operations, totaling 51.6% and 53.4% of owner-problems reported in 2005 and 2015, respectively.

Organizers hope these survey results will help the horse industry direct financial support of equine research projects, the need for which remains high. One possible consideration is reconvening a research summit, which in 2006 assembled scientists from universities, foundations, and corporations involved in equine research to develop recommendations to increase medical research.

In response to the 2006 summit’s top recommendation of increasing funding by creating a uniform message for owner education about the cost and benefits of research, the AAEP Foundation with assistance from the Equine Research Coordination Group, created position papers aimed at increasing public awareness of the need for equine research. Other summit recommendations included increasing collaboration among researchers and funding for graduate student stipends to train future researchers.

High-Energy Horse Feeds

A performance horse’s diet must supply all the energy to remain at his best. But achieving that can be easier said than done. Here’s what to remember.

high energy horse feeds

The importance of nutrition for optimal athletic performance, regardless of the level of competition, cannot be over-emphasized. We should on occasion refresh our understanding of some basic concepts and look at ways to meet the nutritional needs of the athletic horse. The first key concept seems obvious, but nonetheless is critical to understanding feeding the performance horse—the energy needed to run and jump ultimately comes from the food the horse eats. The old adage “you are what you eat” rings true when we think about feeding for performance.

The second important point is that energy is by far the most important consideration when designing a diet for a performance horse. Yes, the diet must supply all the essential nutrients in appropriate quantities, and it is often necessary to supply various additives or supplements to ensure that the horse receives adequate amounts of vitamins and minerals. Nonetheless, it is the number of calories eaten that has the greatest bearing on a horse being able to perform to the best of its ability. If there is inadequate energy in the diet of a horse in training, he will lose weight and his performance will be subpar.

The daily energy needs of the high-performance horse (e.g., a racehorse, a three-day event horse, or an endurance athlete) can be more than twice those of the average “couch potato” horse. You need to provide your horse with adequate “groceries” so that he can maintain body condition during the rigors of training and competition. Here’s where it can get tricky—the horse’s digestive tract is primarily designed to extract energy from the feedstuffs available in its natural habitat—green grass. However, the high-performance horse simply cannot consume enough forage (pasture or hay) to meet his daily energy requirements. Therefore, we reach for more energy-dense feeds such as grains and fats to correct the energy deficit. All too frequently, however, the tendency is to overfeed grain and underfeed forage, the end result being increased risk for digestive upsets and, in some horses, recurrent problems with the muscle disorder tying-up.

How Much Energy?

Energy isn’t a nutrient. Rather, it is a measure of a feed’s potential to drive body functions. Nutritionists refer to dietary energy in terms of kilocalories (kcal, equal to 1,000 calories) or megacalories (Mcal, where 1 Mcal=1,000 kcal) of digestible energy. Digestible energy (DE) refers to the amount of energy in the diet that is absorbed by the horse. Digestible energy requirements are calculated based on the horse’s maintenance energy requirement—the amount needed to fuel all basic body functions—plus the additional energy needed for activity, such as running and jumping. The main sources of energy in the diet are starch, fat, protein, and fiber. All of these sources should be used in the diet of athletic horses, but they should be combined in specific ratios for optimal performance—more on this later.

Just how much energy does the performance horse need? According to the National Research Council’s Nutrient Requirements for Horses (2007), a non-working, 1,100-pound (500-kilogram) Thoroughbred needs roughly 16 Mcal of DE per day. Horses in light work (one to three hours of riding per week) should consume about 20 Mcal DE per day. Horses in this group include “weekend warriors” or recreational trail mounts. Horses in moderate work (three to five hours of work per week, with some skill work such as jumping or cutting) require roughly 23 Mcal DE per day. Horses in this category include show horses, polo ponies, and ranch horses. Horses in heavy work (four to five hours of riding per week, with substantial portions spent at the canter or doing skill work) need about 26 Mcal DE per day. Horses in this category include low- to mid-level eventers, some racehorses, and frequently shown horses. Finally, horses in very heavy work (six to 12 hours of work per week) require around 34 Mcal DE daily. These are racehorses, elite three-day eventers, and combined driving horses.

To understand why the performance horse cannot thrive on forage (pasture or hay) alone, let’s do some simple arithmetic. A medium-quality timothy hay provides about 0.8 Mcal of DE per pound. For our Thoroughbred racehorse to meet his DE needs (say, 32 Mcal), he would need to consume 40 pounds (18 kilograms) of hay per day—pretty much an impossible scenario. For one, the horse is not physically able to eat that amount of hay. In fact, he cannot eat even half that amount. As well, high forage intakes result in development of a “hay belly,” which is an undesirable characteristic in a high-performance horse.

From Mouth to Muscle

Ultimately, the chemical energy obtained from the diet must be converted into mechanical energy in muscle. During exercise, there are two primary sources of energy—glucose and fatty acids. The horse’s body uses these fuels in different forms and at different sites. Fats are stored in adipose tissue, as well as in and around muscle fibers, while glucose is stored as glycogen in muscle and in the liver. The type of fuel used during exercise will depend on work intensity, the muscle fiber makeup of the horse, conditioning status, and to some extent, diet.

A few points need emphasis here. For galloping exercise, muscle glycogen is by far the most important fuel for muscle contraction. In fact, during racing muscle glycogen probably provides more than 80% of the horse’s energy. Conversely, minimal energy will be contributed by fat during all-out galloping. Fat is a much more important fuel during lower intensity exercise, such as trotting and cantering.

Also realize that a horse’s body can’t synthesize glycogen from fat—he needs carbohydrates from grains or fiber sources to replenish liver and muscle glycogen stores. Regardless of exercise discipline, muscle glycogen is an important energy source. Horses will use a substantial amount of fat during endurance exercise where trotting and cantering are the primary gaits. However, glycogen is still vitally important because depletion of muscle glycogen stores will result in premature fatigue. Similarly, there is evidence that low muscle glycogen will impair high-intensity exercise performance. Therefore, although there are some real benefits to adding fat to the diet of a performance horse, there must be an adequate supply of carbohydrates to allow restoration of glycogen stores.

Dietary Energy Sources

Energy in the diet is provided by four components—starch, fat, fiber, and protein:

  • Starch, a carbohydrate, is the primary component of cereal grains (oats, corn, and barley). Oats are about 50% starch, while corn and barley have more than 60% starch. Starch is the dietary energy source of choice for glycogen synthesis. During digestion, starch is broken down into glucose, which is then absorbed into the bloodstream and made available for glycogen synthesis in muscle and in the liver.
  • Fats, such as corn oil, soybean oil, or the fat contained in stabilized rice bran, are the most common sources of fat in the performance horse’s diet. On a weight-for-weight basis, fat contains roughly 2.25 times as much energy as corn, oats, and barley. In particular, vegetable fats are very palatable and highly digestible. Fat is particularly useful for horses which cannot or will not eat enough of the more traditional feedstuffs (hay and grain), the result being a steady decline in body condition and performance. Adding fat will increase the energy density of the diet so that a lower feed intake is required to maintain body weight. Adding fat also allows you to feed less grain, thereby helping to reduce the risk of digestive upsets associated with excess grain feeding.
  • Fiber, found in hay or pasture, is an energy source that is often overlooked in horse nutrition. The horse’s hindgut is designed to ferment plant fiber, the main products of this process being volatile fatty acids (VFA). In the liver, these VFA can be used directly for energy, or converted to fat or glucose. Adequate dietary fiber is also essential for maintaining gut health and, in endurance horses, the large water and electrolyte reserve created by a high-fiber diet (which soaks up a lot of water that can be utilized later) can be used to stave off dehydration and electrolyte imbalances during exercise. However, not all fiber sources are created equal. Poor-quality hay contains large amounts of lignin, a nondigestible fiber. At the other end of the spectrum are the so-called “super fibers,” such as beet pulp and soybean hulls. These fiber sources have the same beneficial aspects as forage fibers for maintaining gut health, but contain more energy. In fact, beet pulp or soy hulls provide as much energy as oats. Therefore, use of these super fibers gives us another means for reducing a horse’s grain (starch) intake without compromising overall energy in the diet.
  • Protein is not a primary energy source and, unlike fat and carbohydrates, is not stored in the body. However, if dietary protein is in excess of the horse’s needs for synthesis of body proteins, some protein will be used for energy. For several reasons, though, very high-protein diets are not recommended for horses. First, water requirements increase with increased protein intake. Second, metabolism of protein in excess of requirements causes a build-up of nitrogen end-products (ammonia and urea) that can contribute to health problems. For example, high urinary ammonia can irritate the horse’s lungs, contributing to chronic airway diseases.

Feeding Strategies

Enough of the theory—how do you safely meet the energy needs of the performance horse? One of the first considerations is how much feed we expect a performance horse to eat each day. The 2007 National Research Council text Nutrient Requirements of Horses provides guidelines for both the total amount of feed (hay and grain) that should be consumed by working horses and the ratio of forage to grain in the diet.

The intake estimates are reasonable. For example, a working horse in the intense category (the high-level performer) will be expected to consume somewhere between 2% and 3% of its body weight as feed per day (22 to 33 pounds for a 1,100-pound horse or 9.9 to 14.9 kilograms for a 500-kilogram horse).

However, the ideal ratio of forage to concentrate will vary depending on the availability and energy content of the forage. Remember that alfalfa, on average, has a higher energy content than grass hay. Therefore, when alfalfa is the predominant forage, it is possible to feed more forage and less concentrate compared to a situation where lower-quality grass hay is fed.

Forage must form the foundation of the diet, as adequate fiber intake is essential for maintenance of proper gut function. A general recommendation is that the horse should receive at least 1% of its body weight per day as hay (or an alternative forage)—that’s 11-12 pounds for our 1,100-pound horse. Feeding below the minimum forage amount might increase the risk of gastrointestinal problems such as colic and gastric ulcers. It is also desirable to give the horse free access to forage—the saliva produced when a horse nibbles on hay helps buffer gastric acidity. Allowing the horse to snack on pasture or hay throughout the day might reduce the incidence or severity of gastric ulceration. Feeding one of the newer grain concentrates that contains a super fiber, such as beet pulp, is another way to increase fiber intake.

Most commercially available grain concentrates contain all the major energy sources—starch, fat, fiber, and protein. As mentioned, don’t view protein as a primary energy source. Protein requirements are around 10% of the total diet, although in most cases protein intake will be higher given the protein contents of common feed ingredients—oats at 11.5%, corn at 9%, timothy hay at 6-10%, and alfalfa hay at 15-20%. A concentrate with 10-12% protein is fine in most circumstances.

As much as possible, make use of fat and one of the “super fibers” to raise the energy content of the diet. Yes, some starch is required to provide glucose for synthesis of liver and muscle glycogen. However, there is an upper limit on the amount of grain that should be provided in a single meal. As a general rule, a single meal should contain no more than five pounds of grain. If larger amounts of starch are fed, the capacity of the small intestine to digest and absorb the starch can be overwhelmed such that a substantial amount of the starch passes into the large intestine. Within the large intestine, this starch will be rapidly fermented to lactic acid by bacteria, with the attendant risk for development of colic or carbohydrate overload-induced laminitis.

One way to reduce excessive starch in the diet is to feed beet pulp or soy hulls, which are low in starch. Soy hulls are used in pelleted feeds, while beet pulp is often incorporated into “sweet feed” mixes. Both of these fiber sources are quite palatable. A grain concentrate with added fat also helps reduce the starch content of the diet—those with a fat content between 7-10% are optimum for most performance horses.

Some commercial grain concentrates contain both fat and a super fiber. Currently, feeding this type of feed is the best approach to meeting the high-energy requirements of the performance horse.

The amount of dietary starch will need to be more drastically restricted when dealing with a horse which has recurrent tying-up problems, particularly Thoroughbreds with recurrent exertional rhabdomyolysis. In those horses, high-starch diets appear to contribute to tying-up problems. Diets for those horses should emphasize the use of good-quality hay, highly fermentable fibers (beet pulp or soy hulls), and fat, with a smaller amount of starch (not more than five pounds of grain per day).

Water and Electrolytes

Other important dietary considerations for the performance horse are water and electrolytes. An average size non-working horse needs about six to eight gallons (20-30 liters) of water per day. Daily workouts can greatly increase water needs, as sweating followed by evaporative cooling at the skin surface is the primary means by which horses rid themselves of excess body heat. In hot weather, sweat fluid losses can be in excess of 10 liters per hour of exercise. As a result, the daily water requirements of a performance horse might be 50-60 liters or more. Ensure that plenty of fresh water is available at all times, and take advantage of the horse’s desire to drink after exercise.

Sweat is also rich in electrolytes, particularly sodium, potassium, and chloride. As most forages and grain concentrates are relatively low in salt, some form of electrolyte supplementation might be necessary for high-performance horses, particularly in the summer months when sweat electrolyte losses can be high. Be aware that not all electrolyte supplements are created equal. Some supplements contain a great deal of sugar (as sucrose or dextrose) and only small amounts of actual electrolytes. As an alternative, you can use common table salt or a 50:50 combination of table salt and “lite salt” (potassium chloride). Feed up to two to three ounces per day, divided into the morning and evening feeds.

Keep your performance horse’s diet within these parameters, and he’ll have the nutritional tools to do whatever you need him to do.

About The Author


Ray Geor, BVSc, PhD, Dipl. ACVIM, is the pro vice-chancellor of the Massey University College of Science

Minimizing Foal Stress Levels in the Breeding Shed

What would be the best plan for handling a foal whose dam is being covered by a stallion?

Minimizing Foal Stress Levels in the Breeding Shed
Q.What would be the best plan for minimizing foal stress levels in the breeding shed when his dam is being covered by a stallion? Every farm seems to have their own way of handling the foal during live cover.In one facility I worked at the foal was kept in a padded pen in the corner of the breeding shed. That was pretty good in that you knew it was safe and contained, except that the foals I saw in that setup fussed the whole time, mostly calling and trying to climb out of the pen. And when the stallion mounted the mare, some foals seemed to become frantic. And then everyone got upset. Another way I’ve seen is to have a person hold the foal off to the side of the breeding shed. That also was usually okay at first, but it was difficult to calm the foal after it got upset about the stallion jumping on the mom.

Both ways seemed pretty upsetting for the foal, and it could not be helpful for the mare to be concerned about her stressed foal. Some farms say that’s why they like to have the foal in the trailer or in a stall far away from the breeding area or even leave it back at the mare’s farm. Couldn’t that be just as traumatic for both the mare and the foal, though?

Via email

A.This is one of the most frequently asked questions about the logistics of natural breeding, and minimizing foal stress levels in the breeding shed is important.

First, it’s difficult to say which method is more stressful for the foal, the dam, and the staff. Different foals at different ages might do better or worse with any of those practices you described.

Frisky Foals

One thing I’m glad you brought up was your observation about the foals becoming very animated at just the moment you want them to be still; this is a reliable phenomenon. That scramble to mom just as the stallion approaches for mounting is a natural instinctive response seen in horses breeding under natural social conditions. Under natural social conditions, of course, the foal is present and unrestrained. Most of the time, foals seem to hardly notice the breeding itself, since breeding is so quiet under natural conditions. The foal is around the stallion in a familiar environment 24/7, and mares are bred over and over whenever in estrus. So it is not all that new or unusual for the mare and foal. But should there be any excitement that gets the foal’s attention, as there almost always is under domestic breeding conditions just at the moment of mounting, foals—particularly young ones—scoot to stand in front of and perpendicular to their dam’s chest. The position in front of mom’s chest seems to be the safest and most “out of harm’s way” for the young foal, and it seems to be reassuring to the dam that the foal is in a good place.

So that burst of animation to get to the dam seems almost reflexive, elicited by that little nicker vocalization the stallion makes in those last seconds of teasing the mare just before lifting his forefeet off the ground to mount. Some mares will actually vocalize to the foal at that moment, as if to say, “Where are you? Get over here.” Based on this understanding of natural behavior, my recommendation is to organize the domestic breeding situation to be able to accommodate this natural behavior as much as is safely possible.

Leaving Foals at Liberty

Working in a large area is far better than a small one. Allow the foal to follow along unrestrained into the breeding area with its dam. Some foals tend to hug close to the mare, while others explore around as is natural and expected for foals in a new nonthreatening environment. When the stallion enters, the foal is likely to either continue exploring and playing about the room, or he may go closer to the head of the dam. Some may nurse or nuzzle their dam’s udder. This appears to be reassuring to both the dam and the foal. The handlers holding the mare need to be aware of and prepared for the foal to scoot into position at the mare’s chest.

When the foal is at liberty in the breeding area, it is essential to have the area especially uncluttered and otherwise “baby-proofed.” A comfortable, unworried foal is inevitably curious and attracted to any novel objects. The excitement of the stallion entering the shed may stimulate a burst of playful romping, just as if an unfamiliar stallion were to approach a family group under natural conditions. If available, designate someone as the foal-minder, just to keep an eye on the foal and to quietly guide it away from any inadvertent chances to get into trouble as it explores the breeding area. If the stallion comes in gangbusters-style, or if there is any sort of ruckus, the foal is more likely to run to the dam, which will tend to calm them both. The foal may display that submissive “I’m a baby” nursing posture and clap its mouth toward the stallion—again, a natural behavior.

Keeping Foals Restrained or Elsewhere

Some establishments find the concept of an unrestrained foal in the breeding area too far out of tradition for their staff or clients, or they worry about the foal’s and personnel’s safety. An alternate approach that can usually work almost as well in terms of reduced stress, both for the mare and her foal, is to have someone cradle the foal as close to the mare as safely possible, a bit to the off side and in front of the mare. The point is that the foal and dam can be as close as possible and certainly be able to see and hear each other, rather than off in a corner or in a pen. If the foal should struggle to get to the dam, the person holding the foal can make a decision at that juncture whether to hold on, move with the foal, or let go and allow the foal to go the mare’s chest.

For those who really prefer to contain the foal in a pen, it can help to have it as close as possible to the mare and especially where the mare and foal can see and hear each other.

Leaving a foal on the trailer or in a stall outside the breeding shed can work for some mare and foal pairs. There is some research suggesting that having a person stay with the foal can reduce signs of stress.

Of all the variations you mention, my least favorite is to leave the foal at home, unless the stallion is only a few minutes away, and it can be kept with some other familiar horses or with a familiar caretaker while the mare is gone. If nothing else, going along for the ride can be a good opportunity to become acclimated to transport.

About The Author


Sue M. McDonnell, PhD, is a certified applied animal behaviorist and the founding head of the equine behavior program at the University of Pennsylvania’s School of Veterinary Medicine. She is also the author of numerous books and articles about horse behavior and management.

The Medication Conundrum: Drug Regulation Challenges in the Horse Industry

Learn about the current challenges of medication regulation and drug testing in the race and sport horse industries.

The Medication Conundrum

Current drug regulation challenges race and sport horse industries face

Ernest Hemingway traveled with his new bride to Paris for the Christmas holiday in 1921 and wound up staying there for five years. It was the best place to be during the early 1920s and hosted a rich community of prominent writers. Hemingway filled one blue notebook after another with his writing, and when he had spare time he went to the races. An astute handicapper could make decent money betting, he wrote in A Moveable Feast, especially if a person paid close attention to the “boosted horses.”

There was widespread use of performance-altering drugs, Hemingway explained, but identifying the doped horses in the paddock before a race was difficult. Some—the ones that reacted badly to the drugs—were easy to pick out, but the writer often had to rely on tips from insiders. A rudimentary saliva test to detect a few prohibited drugs already was in use in France by the early 1920s, but hardly ever at the tracks Hemingway frequented. It would be another decade before a modified saliva test made its way across the Atlantic to Hialeah Park race track, in Florida.

By the early decades of the 20th century, horse racing’s drug problem had become the sport’s most poorly kept secret. The Jockey Club, the breed registry for Thoroughbred horses in the U.S., Canada, and Puerto Rico, had approved a rule against doping in 1897 but, without a reliable test for illegal drugs, enforcement was problematic and relied on either a witness or a confession. Newspapers railed against the practice, but public indignation was rare. It took the work of a displaced G-man to change things.

The war on illegal drugs in U.S. racing began in earnest during the early 1930s. Leading the campaign was Harry J. Anslinger, who had moved from the soon-to-be-obsolete Commission of Prohibition to head the Treasury Department’s new Bureau of Narcotics. The Bureau was established to stem the tide of illegal drugs sweeping into the U.S., but Anslinger also was concerned about what he saw as the proliferation of drug use among backstretch workers and the doping of horses at the country’s racetracks.

By 1933 Anslinger’s investigators reportedly had gathered evidence—through witness statements or ­confessions—of more than 200 horse doping incidents, some at major tracks involving prominent horsemen. Acting on that evidence, federal narcotics agents conducted a series of well-publicized raids at tracks up and down the Atlantic Coast and in the Midwest that resulted in indictments and arrests of owners, trainers, jockeys, and stable workers. The charges generally were based on possession of illegal drugs, however, rather than attempts to influence race outcomes. Without a test for illegal drugs, there still was no way to prove a horse actually had raced with prohibited substances in its system.

An editorial in Blood-Horse magazine following the raids called out everyone in racing—starting with owners, trainers, and jockeys and moving on to regulatory ­officials—to stop the rampant doping. The next year Hialeah president Joseph E. Widener took up the challenge, imported the French saliva test, and began using it at the Miami track. The result was a horsemen’s ­rebellion.

Amid growing concerns about the new drug testing procedures and enforcement of the “absolute insurer rule,” holding trainers responsible for the condition of horses in their care, the trainers threatened a strike for Florida Derby Day. Widener vowed to stage the closing-day card, and when several strike leaders were barred from the track, the races filled.

Tests for prohibited medications today are more reliable and sensitive, and the absolute insurer rule remains the principal enforcement tool for assigning responsibility after a positive test result. Doping has become more sophisticated as well, however, both at racetracks and at sport horse competitions, and despite an almost perfect record in court, legal challenges to the absolute insurer rule continue.

The disqualification of Kentucky Derby winner Dancer’s Image in 1968 after testing positive for the anti-inflammatory phenylbutazone led to years of legal challenges and sweeping changes in track security, testing procedures, and enforcement. In 2018 a Kentucky court ruled that the state’s absolute insurer rule was unconstitutional. An appeal of that decision was pending as of this writing.

The Scope of the Drug Problem

Taken at face value, horse racing’s doping numbers are fine—better than fine, really. In 2014 the Association of Racing Commissioners International (RCI) released one of the most comprehensive reports on testing for prohibited substances in the U.S. The RCI reported that 340,932 “biological samples” were sent to testing laboratories around the country in 2013.

The results were impressive: From those tests there were only 1,140 medication violations, a “clear rate” of 99.67%. Compared with testing for prohibited substances in human sports, racing’s labs tested more samples and still fared slightly better than the United States Anti-­Doping Agency (clear rate of 99.55%) and the World Anti-Doping Association (clear rate of 98.97%). Horse racing’s clear rate was almost as good two years later, 99.63%, according to 2015 Racing Medication & Testing Consortium (RMTC) statistics.

Supporters of racing’s current regulatory scheme could point to the numbers and reasonably ask, “what drug problem?” Skeptics might point to the same numbers and reasonably caution, “not so fast.” To make sense of the statistics, we must put them in context. Not every horse in every race is tested. That would be impractical and prohibitively expensive, with the cost of drug tests running as high as $200 or more per horse in some jurisdictions.

The Jockey Club reported that 43,139 races were run on the flat and over jumps in the U.S. in 2013. Winners of those races account for at least the same number of tests, and perhaps as many as twice that number because RCI reference to tests on “biological samples” could include blood and urine samples from the same horse in a single race. Also included are tests done on “out-of-competition” samples, rather than on those taken post-race.

Every state tests every winner, plus some nonwinners chosen because of suspicious performance. Other horses are chosen for testing at random. A result of this selective testing is that racing’s impressive clear rate is representative of the population of horses racing or in training, but necessarily incomplete. A comprehensive clear rate, a number that truly represents how many horses are running with prohibited medications in any given race, might be better or worse than the published numbers. Until racing authorities come up with unlimited funds for testing, though, we can’t know for sure.

This potential discrepancy is not necessarily a serious problem, though, says RMTC executive director Dionne Benson, DVM, JD. “The challenge is money,” she says—not enough money to cover the laboratory fees and labor costs associated with testing every horse in every race. “Given the inherent restrictions, the goal of drug testing is not to catch every cheater. The goal is to discourage people from cheating in the first place.”

Testing every winner, plus some nonwinners picked at random, along with out-of-competition testing, is a “tactical solution” that keeps the cheaters guessing, never knowing whether a horse will wind up in the testing barn after a race.

Also encouraging, Benson adds, is the nature of the relatively few violations. Most are for therapeutic medications being used to treat a medical condition, rather than an attempt to cheat.

Clear rates in the sport horse world are comparable to racing’s numbers, ranging annually from 0.5 to 1.5%, says Stephen Schumacher, DVM, chief administrator for US Equestrian’s Equine Drugs and Medication Program. Facing the same financial constraints as racing’s ­regulators—not enough money for all the testing they’d like to do—US Equestrian follows a similar “tactical” approach, but with a few important differences.

The Medication Conundrum

“We’re all trying to do the same thing—to identify drug abusers,” Schumacher says. “In racing, they’re always looking for ways to make horses run faster and farther, but in our sports it’s different. They’re usually looking for ways to make horses jump better or perform better in an under-saddle class.”

In racing, the horse that runs fastest crosses the finish first. At a horse show, measuring success is more complicated, with blue ribbons in untimed events based on a judge’s subjective opinion. Sport horse regulators also enjoy more discretion in selecting horses for testing than their colleagues in racing, where rules dictate testing all winners. Without that requirement, drug testing at shows can be directed toward perceived problem areas in a class, division, or event, with targets changing as conditions dictate.

“An inherent challenge for us is that our competition venues often change on a weekly basis,” Schumacher says. “We use independent contractors who select horses for testing and collect samples, and there always is the possibility for unintentional sampling bias. We don’t have the resources to test every horse in a class, and we don’t always test the winner of a class. This means that at times we might select a horse for testing that does not have prohibited drugs on board and not select a horse that does. But we’re always trying to use our resources in a more focused way, and we do our best to maintain the random nature of the testing to deter the violators.”

One Step Forward, Two Steps Back

Benson and Schumacher agree that one of the most frustrating aspects of their work is the inability to see into the future and to know which new drugs to test for before they get used in competition. Regulators are constantly playing catch-up.

“We can only look for what we already know to look for,” Benson says. “Identifying a new drug in the laboratory often isn’t difficult, but you may never see that drug when you start actual testing. You may only see the metabolites of that drug, and deciding which metabolites to look for complicates the process. Running a drug sample through a machine is not the same as running that drug through a horse.”

New challenges also include developing effective ways to detect selective androgen receptor modulators, a group of drugs developed during the past few years to increase muscle mass in human athletes, and “blood doping” with erythropoietin (EPO), says Benson. The emergence of new therapeutic medications that have legitimate uses in veterinary medicine compound the problem for regulators when the same drugs are misapplied as performance enhancers in horses.

“You’ll get frustrated if you look at progress in short increments,” she says.

Schumacher and his cadre of scientists, testing veterinarians, and technicians face the same problem.

“People often ask me how it feels to be two steps behind,” he says. “Sometimes, I’d love to be only two steps behind.”

A Federal Solution?

Anslinger’s interest in racing and backstretch raids was short-lived. Already in the process of shifting the Narcotics Bureau’s full attention toward illegal drug trafficking for human consumption, his promised federal interventions into positive drug tests in racing never ­materialized.

Medication regulation in racing started at the state level with Widener at Hialeah and stayed there. Rule-making for drug testing and enforcement in the English sport horse world, on the other hand, always has been the responsibility of private organizations, such as US Equestrian in this country and the Fédération Equestre Internationale internationally.

Legislation to shift responsibility for drug testing and enforcement from individual states to a single federal agency was introduced in Congress for the first time in 2015, but it never gained traction. Now, with prominent horsemen’s groups on both sides of the issue and millions spent in lobbying, that legislative indifference might be about to change.

On May 25, 2017, the Horseracing Integrity Act of 2017 was introduced in the House of Representatives. Like earlier legislative efforts, the new version offered a federally mandated solution to racing’s drug problems through the formation of an oversight agency and the institution of uniform medication rules across all racing jurisdictions. A Congressional Subcommittee hearing, a preliminary step in the legislative process, was held on June 22, 2018, but no consensus has emerged.

The most divisive question, and the issue most likely to stall the bill before it reaches a vote, involves race-day administration of Lasix, a popular medication used to prevent or reduce the effects of exercise-induced pulmonary hemorrhage (EIPH, or “bleeding”). The current version of the Act would eliminate Lasix administration on race day, and finding an acceptable middle ground is proving difficult.

A much touted benefit of centralized regulation is rules uniformity across the country. Whether this will be successful in solving the problem depends on how you feel about drug testing thresholds. A threshold is the maximum level of a prohibited medication that is assumed to have no effect on a horse’s performance, and the current jigsaw puzzle of regulations might have different thresholds for the same drug from state to state. A concentration below the threshold is not considered a drug “positive.” The most restrictive type of regulation is zero tolerance, with no thresholds and a positive result for the smallest trace of any prohibited medication in a horse’s system. Proponents of a total ban on race-day medication include the Water, Hay, Oats Alliance (WHOA), a national organization supported by a number of leading organizations and individuals.

While everyone wants a level and safe playing field, there are disagreements about how to get there. Many horsemen’s groups and veterinary associations strongly oppose a race-day ban on Lasix and argue that the legislation would create an equine welfare crisis by eliminating an effective treatment for a common problem. For the Act’s many supporters, the legislation’s intent is to protect the sport’s integrity and to reverse much of the public’s low opinion about horse ­racing.

The Medication Conundrum

Vets on the Ground

Regulation of prohibited substances in both racing and showing is a continuum: The policymakers who write the rules are at one end; the enforcers who collect and test samples and administer the regulations are the middlemen; and at the end are the practicing veterinarians who often are far removed from the rule-makers but still bound by the regulations.

Jeff Blea, DVM, is a partner in VonBluecher, Blea, Hunkin Inc. Equine Medicine and Surgery, a racetrack practice in Sierra Madre, California. He also is a former president of the American Association of Equine Practitioners, an organization that opposes the Horseracing Integrity Act. Blea supports the idea of uniform medication rules, one of the Act’s goals, but he isn’t convinced that federal intervention is the answer.

“Uniformity in the rules is what we need,” Blea says, “and we’re getting there. We have a program in place, and we’re already marching toward uniformity.”

Racing commissions have adopted the RMTC’s National Uniform Medication Policy (NUMP) in full in 11 states and in part in 21 other jurisdictions. One set of rules, applied in every racing state, will help eliminate confusion for veterinarians when horses ship from track to track.

“The better horses will run in races all across the country,” Blea says. “And part of a veterinarian’s responsibility is to know the rules. If one of our horses is going to a state that has adopted the uniform rules, I already know that the rules there will be the same as mine here in California. But if not, I might have to call someone in that state and ask about the rules.”

The biggest challenge moving forward, he adds, is better public relations for a program that already is working.

“We have to communicate to the public that things are improving,” he says. “So many things have come about in the last few years. We need to tell the world what we’re doing and why we’re doing it and then keep telling them.”

On the other side of the country, on Long Island, Sara Langsam, VMD, is a partner in the New York division of TFB Equine. She divides her time between New York and Kentucky and has experience navigating the regulatory waters from state to state. The NUMP has helped bring a measure of consistency to regulations in many jurisdictions, Langsam says, but the process is “going more slowly than anyone imagined.” (Inconsistent regulations typically are not an issue for sport horse competitors, who in most disciplines compete under the same rules no matter where the competition is held.)

“The inconsistencies in the rules can be frustrating,” she adds, “especially with clients who are racing in several states. The different regulations affect a lot of the day-to-day work you do. You have to know what the expectations of the owner and trainer are for a horse. Is there a possibility that the horse will be racing anytime soon, and where? You have to do your homework, so you can advise your clients properly and professionally to avoid a positive test.”

About federal intervention in drug regulation, Langsam is guardedly optimistic.

“It’s okay if it brings uniformity,” she says, “but it has to be done properly, and we need good voices to speak for our industry. The boots on the ground, the people who live it every day, we understand our industry better than anyone else. And we know it’s a pretty clean sport.”

A persistent worry across the industry is that prohibited substances might be used to supplant good horsemanship.

“There are always bad actors out there who reach for something in a bottle or tube to improve performance, rather than focusing on the training, fitness, and welfare of the horse,” Schumacher says. “But we emphasize that the vast majority of our trainers and members strive to comply with our drugs and medications rules.”