Equine Cushing’s: Case by Case

Cushing's, Case by Case

Learn how veterinarians diagnosed and managed six real-life equine Cushing’s cases.

We all know what a horse with equine Cushing’s looks like, right? He’s an old retired guy with a long, curly coat and sore feet. He’s kind of fat in some places, skinny in others.

This type of “textbook” case, however, is far from standard. Also known as pituitary pars intermedia dysfunction (PPID) or hyperadrenocorticism, equine Cushing’s disease leads to an overproduction of hormones such as adrenocorticotropic hormone (ACTH) and cortisol. Classic signs include, yes, an abnormal hair coat and a failure to shed, but also abnormal sweating, loss of muscle mass, and increased water intake and urination, among others.

If and when Cushing’s horses get to the point of looking like the stereotypical case, it’s often in a very late stage of the disease, veterinarians say. And as with many illnesses, the longer we wait, the harder it is to fix.

The good news is the opposite is also true, says Sabine Ware, BVSc, CERP, equine veterinarian at The Vet Practice, in Victoria, Australia. When diagnosed early and treated promptly and properly, PPID horses have the best chance of leading normal lives.

Melissa Restifo, DVM, Dipl. ACVIM, internal medicine specialist at Brandon Equine Medical Center, in Florida, agrees. “Diligent owners are paramount for that,” she says. “They pick up on subtle signs, meaning we can treat the disease before it becomes a real problem.”

In this article Ware and Restifo share real-life stories of Cushing’s horses they’ve treated that stray from the classic scenarios.

Andy: The lethargic one with changes in body shape

12-year-old Australian riding pony cross gelding

Andy was a “very loved pet” who had been used for leisure riding and harness driving. A plump sorrel pony gelding with a body condition score (BCS) of 5 out of 9, he stood about 14 hands.

“He was the calm soul of the farm, with a kind eye and relaxed personality among a farm full of high-spirited dressage horses,” Ware says.

Andy’s owner first noted that her pony was developing strange white spots, about 2 inches in diameter, across his body. “His coat was quite short and shiny, and overall he looked like a healthy pony,” Ware says. “He didn’t have that long curly coat that most people consider to be classic.”

Over the next few months he became increasingly lethargic and finally “ended up with a big, pendulous abdomen,” she says. About the same time he came down with subtle signs of laminitis, a common side effect of PPID if affected horses’ insulin levels are high. “He didn’t get excruciating pain—just increased pulses (in the feet) and very slight (hoof) changes,” she says. “In general, all his signs were mild and vague.”

Indeed, this confusing case didn’t shout “Cushing’s” in the beginning, says Ware. At first she suspected a viral or an immunosuppressive disease and tested accordingly. She also tested his thyroid function and for insulin resistance (IR, a decrease in tissue sensitivity to insulin that often accompanies PPID). And, just to be sure, she ran an ACTH test for equine Cushing’s. The tests showed Andy had both PPID and IR.

Ware started Andy on a daily low dose of the FDA-approved PPID drug, pergolide, which comes in tablet form and is designed to lower ACTH production. She and Andy’s owner also put him on a restricted diet to control his IR.

Within a year the pony transformed completely despite a few initial laminitic flareups. “All his spots went away, his abdomen tucked back up, his laminitis got under control, and he went back to being his brighter self,” Ware says.

Andy benefited from his medication over the next four years, feeling great. He was euthanized due to an unrelated injury at age 16.

Collaborating to Make Horse Racing Safer

Collaborative efforts among horse health researchers, the racing industry, and governments could lead to effective measures that will improve safety for both horses and jockeys, one equitation scientist says.

horse racing

Racehorse falls can be catastrophic for both horse and jockey. But collaborative efforts among researchers, the racing industry, and governments could lead to effective measures that will improve the safety of both athletes.

“When a jockey dies during a horserace, there is a profound effect—socially and financially—and the same is true when a horse dies,” said Peta Hitchens, PhD, epidemiologist at the Melbourne Veterinary School Equine Centre at the University of Melbourne, in Australia. Hitchens spoke on the power of collaboration in improving racing safety and welfare during her plenary session at the 2017 International Society for Equine Science Conference, held Nov. 22-26 at Charles Sturt University in Wagga Wagga, New South Wales, Australia.

“By bringing the various players together to collaborate on this one common goal—safety of rider and horse—we can hope for more efficient and reliable ways to bring the risks of catastrophic injuries and death as close to zero as possible,” she said.

Hitchens said her line of work as an epidemiologist has led her to investigate all the scientific studies over the last three decades reporting catastrophic racing injuries. She’s found that jockeys are 170 times more likely to sustain major injuries—enough to send them to the hospital or at least have to sit out the rest of the racing day—when they ride a horse that “breaks down.”

She’s also picked up on significant risk factors for injury in both racehorses and jockeys. While some of those factors—like the horse’s age—can’t be changed, there are numerous factors that can. Those include:

  • Racehorse training programs: Some are too intense, others not enough.
  • Track surface and quality: Some dirt tracks are too soft; some turf courses are too hard.
  • Horse behavior: Rearing, bucking, and other conflict behavior cause almost all the jockey falls at racetracks before the race has commenced.
  • Medications and doping: Horses under the influence of certain pharmaceuticals are more likely to break down.
  • Racing experience: Lack of experience of the horse and/or the jockey makes falls more likely.

Identifying risk factors is an important step, but getting to actual recommendations on how to improve safety is a challenge, said Hitchens. That’s because many studies contradict each other.

“There are hundreds of articles on racing and welfare, but they often have conflicting information,” she said. “When you’ve got evidence-based information that’s conflicting with other evidence-based information, that makes it hard to give concrete recommendations to the industry.”

By sifting through that research, however, and by working side by side with the industry, the government, and academia in general, she’s getting closer to recommendations. For example, it is recognized that it’s not so much the age of the horse that leads to jockey falls, but that horse’s experience level.

“You can have a 2-year-old that has had at least five starts, and that horse is likely to be safer than a 5-year-old out there having its first race,” she said.

Meanwhile, a jockey’s lack of experience is also going to put him or her at greater risk, she said. “When you combine those risks, they compound, so you’re creating a very dangerous situation by putting an inexperienced jockey on an inexperienced horse, regardless of age.”

Many authorities have no rules about the experience level a jockey must have to ride certain types of racehorses, she said. But those that do are still focusing on the age—restricting young riders from riding 2-year-olds, for example. “That’s something we need to see change,” Hitchens said.

She’s currently focusing in particular on optimizing racehorse training programs, she said. That’s because too little training can put horses at risk of injuries because they’re unfit for the task. Their bones and soft tissues have not had the chance to adapt in preparation for the pressures of an actual race, and this can cause them to sustain an injury.

However, overtraining can likewise lead to catastrophic injuries. “Some race day catastrophes are the result of accumulated damage to bone,” Hitchens said. “The horse is working and training hard every day, racing frequently, and not resting much. So its body doesn’t get time to repair itself. Consequently, you see fatigue damage like microcracks in the bone which can eventually lead to stress fractures. And if such damage to the bone does not get the time needed to repair, that can translate into catastrophic injury on the track.”

Preventing racehorse and jockey injuries is preferable than dealing with the repercussions, she said. For example, although also critical, having an ambulance follow the horses from the time the jockeys mount the horses until they dismount can get the jockeys faster care and thus possibly less severe consequences. But that won’t stop the horses from falling in the first place.

Similarly, the use of a lead pony to the starting gate can prevent the racehorses from acting out dangerous behavior before the race begins. But Hitchens said it’s possible that horses led out by lead ponies might not get an appropriate warm-up they need before the race.

“Having a lead pony could be a ‘Band-Aid’ fix to prevent pre-race falls, but what really needs to happen is that those horses need better training and acclimatization to race-day conditions to manage their behavioral issues while still getting the warm-up they need,” she said.

Working together, industry, government, and research centers can all contribute to helping reduce rates of catastrophic injuries and fatalities to both horse and rider in the most effective way possible, Hitchens said. “When they’re all in it from the start, there’s more sharing, and there’s also more change, because everyone has a sense of ownership in the project.”

The Science Behind Equine Boots and Bandages

What purpose does equine legwear really serve?

Going out for a few jumps in the arena? Buckle on the brushing boots. Heading for a haul in the trailer? Strap on those well-padded, hock-high transport boots. Treating a leg wound? Apply sheet cotton and that brightly colored flexible bandage.

It’s what we’ve seen other people do; it’s what we’ve been taught to do; it’s simply what we know to do. But why exactly do we do it? Of course, the short answer is “protection.” Boots and wraps protect the horse’s limbs. But have you ever asked yourself why or how these dressings protect a horse’s leg—or if they even do? What’s going on under that boot or wrap?

You might be surprised to learn there’s actually very little research about the inner workings of the equine leg when wraps and boots are applied. It’s a growing field that still needs lots of “padding” and extra “layers” of research before we can fully understand it.

But in the meantime, we’ve gone to some of today’s top equine biomechanics researchers to get a better grasp on the science of the wrap and to help us unravel some of its mysteries.

Wrapping Leg Injuries

You know the feeling—when you walk into your horse’s paddock and find the dreaded leg gash. You don’t know how he did it but you do know what to do about it. Bring out the bandages, because nothing says leg wound treatment like good a wrap.

Whether it’s something we’ve learned from experience, from veterinary advice, or from reading about horse care, we know that using padding and bandages to wrap a leg wound is essential first aid. What we might not know, though, is why.

Sure, pressure to any wound will help stop bleeding by encouraging clotting. And a wrap will help protect that wound from contamination. You might also know that wrapping a leg wound can help reduce swelling. In fact, keeping the swelling down could be the most important part of the healing process.

“The equine body’s response to injury in the distal (lower) limb is to swell, which can be protective in some ways (like reducing bleeding immediately after injury) but detrimental if not resolved in the later stages of wound healing,” says Nathan Canada, DVM, MS, Dipl. ACVS, staff surgeon at Texas Equine Hospital, in Bryan.

How does that work? It primarily comes down to a fascinating process of physics, says Canada. “There’s a high-pressure system going through the blood vessels between the heart and the injured area, pumping lots of fluid to that injury,” he says. “But wraps increase the pressure on that injured area from the outside, so that it increases the pressure on the interstitial tissues (those between the cells of structures, in this case beneath the skin) in a way that tries to balance out the (wrap) pressure, so there’s no longer a net force trying to drive the fluid out of the vascular system.”

Bandaging Fundamentals

RELATED CONTENT: Bandaging Fundamentals

He likens a leg injury’s tendency to swell to how a garden hose works. “Think of turning on the hose,” he says. “The water’s going to go from high pressure to low pressure areas.”

There’s also a chemical process going on at the cellular level, Canada says. Essentially, injury-induced inflammation affects the proteins in the bloodstream, which then affect the cytokines (inflammatory proteins) and cellular pathways. Those cause the blood vessel barriers to become “leaky,” allowing more fluid to seep into the surrounding tissues.

“By putting on a pressure wrap, we’re applying pressure to the skin, and that pressure is transmitted to the deeper tissues of the body,” he says. “That will ultimately raise the pressure within that interstitial fluid—(which serves as) the communication channel between the blood vessel and the rest of the body—and make it a more equal plane.”

It works so well, in fact, that the pressure even helps reduce swelling and aid healing of tendon injuries. “Anything you put on the outside of the skin is going to transmit that pressure to whatever soft tissues are underneath it,” Canada says. “So that will help with reducing swelling in tendons and ligaments, although the extent of that hasn’t been investigated. But any time you have a tendon injury, one of the first things you should do is give it support by applying some sort of ­pressure.”

While pressure can be great for leg wounds, the wrong kind of pressure can be detrimental, he cautions. Unevenly distributed pressure—which can come from applying bandages with irregular overlap—can cause pressure peaks that can create direct trauma to the tendon or affect the blood flow to it. This, he says, is a common cause of bowed tendons. Reduce risk by always using padding (e.g., pillow pads) beneath the wrap to help distribute pressure, and keep bandage overlaps as even as possible.

Shipping Boots

Wrapping for Travel

Going on a road trip? Pull out the transport wraps. Again, we experienced horse people know that putting shipping boots or bandages on our traveling horses is just something you do.

But peer pressure isn’t the reason to wrap a trailered horse. Leg pressure, on the other hand, is.

“There actually is a purpose,” Canada says. “Horses were meant to walk around all day, and the blood flow in their legs is dependent on them moving around. So a horse that’s just standing still for long periods of time can ‘stock up’—meaning they get edema (fluid swelling) within their distal limbs.” That swelling can be painful in some horses and even predispose them to getting scratches (the skin infection also known as pastern dermatitis) because the skin becomes fragile.

Pressure from transport wraps can help prevent stocking up in any immobile horse. In essentially the same scientific phenomenon as we described for wrapping wounds, pressure to the legs helps even out blood pressure to keep fluid from collecting in the lower limbs.

How much pressure is necessary? Researchers haven’t come up with a firm answer yet, says Canada. But interstitial pressure is already very low compared to vascular (blood vessel) pressure. So even light pressure, like you might get from the larger, padded, Velcro-strapped transport boots, could prevent fluid buildup.

Another key reason to apply transport boots and wraps is their protective effect against superficial injuries, he says. If the horse gets bustled around in the rig, he could injure his legs on parts of the trailer, step on himself, or even get kicked. The leg coverings could help reduce the severity of such traumatic injuries.

Brush Boots for Impact Protection

Brush boots (also called support, splint, or tendon boots) are the working boots we put on our horses when we ride them—again, often just believing they’re for protection but without really knowing how they protect. These boots come in different kinds of materials, mainly leather and polyurethane, and have a variety of leg coverage and fastening systems.

There’s been little to no scientific ­research into any of these boots’ efficacy, say our sources. But experience leads most horse people and veterinarians to prefer their use, as they’re probably helpful and aren’t harmful (if applied ­correctly).

One thing seems clear about their protective benefits, however: They can shield the legs, and especially the tendons, from impact injuries. As with transport boots, they can provide a cushion against traumatic blows. They have harder surfaces than transport boots, which allows them to distribute stronger forces—which can come from hitting a jump, for example, or from self-inflicted hoof strikes. Large-strided horses sometimes damage their own front tendons by hitting them with their back feet, says Lars Roepstorff, DVM, PhD, professor of equine functional anatomy at the Swedish University of Agricultural Sciences, in Uppsala, and scientific veterinary advisor to the Fédération Equestre Internationale. 

Horse Boots

The boot takes the impact and diffuses the force across its surface, reducing damaging peak pressures significantly. The horse can come out of traumatic strikes with negligible or no injuries, Roepstorff says.

Boots for Preventing Overuse ­Injuries?

It’s a commonly held belief that brush boots can support the large tendons running down the back of horses’ lower legs during exercise. Unfortunately, however, that might not be the case. No research has confirmed this and, biomechanically speaking, it’s difficult to explain how that could even work.

“It’s possible (although unlikely) that if the boot really somehow restricts the downward movement of the fetlock, so that it doesn’t overextend when coming down from a jump, for example, you might get some protective benefit to the tendon,” says Canada. “But even then, it would only be the superficial digital flexor tendon (SDFT). I don’t see how the deep digital flexor tendon (DDFT, which runs beneath it) could be affected at all.”

Roepstorff is even more skeptical. “In the SDFT, the DDFT, and the suspensory ligament, you have a combined strain force of more than 1000 kg (more than 2,200 pounds) when the horse is just cantering—and much greater when he’s jumping,” he says. “Those are huge forces. You don’t support that by just putting something around it.”

It might make us feel like we’re doing something preventive for our horses’ tendons by investing in high-quality boots but, in the end, nothing they wear is likely to stop a tendon or ligament injury from happening. “Brush boots can’t protect the horse from getting overuse injuries, only traumatic injuries,” Roepstorff says.

Temperature Effects

For all the good we hope to achieve through applying wraps and boots to our horses, there’s one important effect that has been scientifically tested—and we still don’t really know whether it’s a good thing or a bad thing.

What we do know is that covering the legs with this kind of equipment causes a temperature increase of up to 30%, probably by trapping the heat inside, says Simone Westermann, DrMedVet, of the University of Veterinary Medicine, in Vienna, Austria. Her team’s study results showed that exercising without boots led to very little temperature increase in the legs compared to covered legs.

While boots and wraps might have some tendon-warming benefits on very cold days, the temperature increase could be damaging to tendons in certain situations. “It cannot be excluded that heat development under a tendon boot during strenuous exercise could be detrimental to the tendon cells,” she says.

Roepstorff agrees. “In vitro (in the lab) studies have shown that extreme temperatures (48°C/118.4°F) decrease survival of tendon cells dramatically. At the same time core tendon temperature has been measured to 45°C (113°F) during high-speed locomotion” he says. “They literally start to melt.”

The consequence is that you don’t need much of an increase in temperature to reach the breakdown stage. “The main cause for tendon injuries (is) of course the force, but I think the heating effect of boots and bandages could increase risk as well,” says Roepstorff.

But don’t panic and throw out the boots just yet. More research is needed to determine the exact advantages, if any, and disadvantages. In the meantime, being aware of the science behind boots and wraps, and recognizing that tradition isn’t always right, is a good start.

“We are living with a lot of presumptions about what these things do, but we don’t really know,” Roepstorff says. “And I’m not sure it’s always good. Clinically we do indeed see a number of injuries due to ill-fitted bandages and protection boots.”

Take-Home Message

When it comes to boots and wraps, there’s little exact science behind how they function in horses. However, physics, chemistry, and biomechanics can give us insight into how they probably work. For the most part they seem to be helpful—at least in preventing swelling and traumatic strike injuries. However, more research will lead us to a better understanding of how useful leg wraps and boots are and how we can best take advantage of them to support our horses’ health and welfare.

About The Author

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Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor’s in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

Can Coastal Hay Cause Colic in Horses?

Find out why this grass is a popular hay for horses and how, in some cases, it might cause problems.

 

Q. I recently rescued two horses and, as I’ve always done with my horses, am feeding orchard grass/alfalfa or timothy hay. My friend is boarding my 3-year-old Quarter Horse gelding while the new ones settle in, and she feeds her horse round-bale coastal hay. I’m concerned about my horse eating the coastal round bale, because I’ve heard that it can cause impactions. Is this true? If so, why, and can I take any steps to prevent it if my horse is eating coastal hay? —Lisa, via e-mail

A. Coastal hay is a type of Bermuda hay that has a reputation for increasing the risk of ileocecal impaction in horses. The belief that coastal hay causes impactions has been around for a long time, and in some cases might be true; however, Bermuda hay can make excellent forage for horses.

Why Bermuda is a Popular Choice

Bermudagrass is native to Southeast Africa and since the early 1800s it has been one of the most important grass species in the Southern United States. Several varieties exist, and coastal Bermuda was introduced to the United States in 1943. A warm-season perennial grass, Bermuda can withstand a wide range of soil types but demands fairly high nitrogen levels. In fact, given adequate moisture, nitrogen is the most limiting factor to forage production, and low nitrogen results in low crude protein content.

The nutritive value of warm-season forages such as Bermuda is generally lower than that of the cool-season grass species such as orchardgrass and timothy. This is particularly true if the grass is too mature when harvested for hay, because this results in higher indigestible fiber. Combined with the fine stems that are typical to some varietal’s, impaction colic risk might increase. The fine stems of poorly digestible hay are thought to act like a clump of hair in a drain, thus causing a blockage.

Reducing Colic Risk

You can take steps to reduce impaction risk. Farmers should harvest Bermudagrass for hay at about three week intervals during the peak growing season. This helps ensure the grass has not become too mature. The greater the maturity of the grass at harvest, the higher the neutral detergent fiber (NDF) content. Researchers have found correlations between high NDF content and increased impaction colic; this is because NDF is a measure of forage digestibility. The higher the NDF, the less digestible the forage. On the other hand, the less mature the grass at harvest, the lower the NDF content, and the more digestible the hay.

The only way to know hay’s NDF content is to have it tested. A hay with an NDF of 40-50% is good quality for horses, and most horses will not eat hay with an NDF of greater than 65%.

There are some varieties of Bermuda, such as Tifton 85, which have courser stems that might reduce the impaction risk. Additionally, in digestibility studies researchers found Tifton 85 had just over 10% greater digestibility when compared to coastal Bermuda, and animals gained and maintained body weight better.

Not all coastal and not all Bermudagrass is going to increase the risk for impaction colic. Coastal Bermuda that has particularly fine stems and harvested when too mature might have an increased risk.

Use common sense when transitioning your horse to new hay. Introduce slowly to allow gut bacteria to adjust to their new fiber source, and supplement with salt to increase water consumption. You might also want to consider feeding a good-quality prebiotic, which could help facilitate plant-fiber fermentation. Also consider feeding other varieties of Bermuda such as Tifton 85.

If your horse has a history of colic, especially those associated with impactions, it would likely be wise to avoid feeding coastal Bermuda hay.

Barn Air Quality Affects Horses’ Breathing

Learn how to make changes around the barn to reduce horses’ likelihood of developing respiratory disease.
Horse looking out barn window

Do dust, pollen, and hay trigger your hay fever? Imagine living where straw and hay are tossed around every day, and it won’t surprise you to learn that horses, too, can get breathing problems from particles in the air.

Hay storage areas and dry bedding materials in stalls contribute dust and particles in the air. The methods used for mucking stalls and cleaning the barn can also reduce or increase airborne particles, says Kara Lascola, DVM, MS, Dipl. ACVIM, an equine internal medicine specialist at the University of Illinois Veterinary Teaching Hospital in Urbana.

“If their bedding is very dry and dusty, or if their stall is located below the door to the hayloft, horses will be at a higher risk of developing respiratory problems, or their existing problems may get worse,” she says.

Further, dust and debris are kicked up when workers use leaf blowers to clean the aisles and muck stalls with dry bedding while the horses are in, which can happen in barns where every horse does not get turned out.

Respiratory Problems Linked to Barn Air Quality

So how do owners know whether a horse is developing a respiratory condition linked to air quality in the barn? And how do they rule out conditions like pneumonia that are caused by more severe diseases?

The two major respiratory conditions that are usually linked to air quality are heaves and inflammatory airway disease, or IAD. These diseases are not accompanied by fever or a productive cough, so those signs would indicate a problem beyond an air quality issue.

Heaves, which is similar to asthma in people, generally affects older horses, while IAD can be seen in younger horses,” added Lascola.

Horses with heaves will also show signs at rest, such as nasal flaring and labored breathing. Like asthma, heaves can be seasonally recurrent, whereas horses with IAD usually cough only while exercising. Horses with IAD also usually have longer recovery times after exercise and can seem winded.

“At present, there aren’t good studies associating specific breeds with each of these conditions,” says Lascola, “but we tend to pick up IAD in young racehorses because they are being exercised so much and conditioned so carefully.”

Diagnostic tests for heaves and IAD can be done either in a hospital or on the farm. A bronchoalveolar lavage is a procedure in which a thin tube is passed into the horse’s lungs to collect a fluid sample containing lung cells for analysis. This procedure can be performed on the farm within a couple of hours. Other diagnostics, such as imaging of the lungs and pulmonary function testing, need to be performed in a hospital, but are fairly short procedures as well. Pulmonary function tests are used to monitor the condition of horses that have already been diagnosed with conditions such as heaves and IAD.

In general, the same environmental changes are recommended to address both heaves and IAD.

Changes to Improve Barn Air Quality

“Cutting down on dust in the air or turning horses out while cleaning the barn can make a huge difference for horses with respiratory conditions,” says Lascola. She also recommends soaking hay to make it less dusty.

For horses in the Midwest or residing around fields farmers use to produce crops, Lascola suggests keeping them indoors during the most active periods of harvesting, especially if the pastures are close to farms and the horses’ respiratory signs worsen during these times.

Things as simple as the construction and layout of the barn itself can change air quality dramatically.

Dr. Kara Lascola

“Everything from the positioning of the doors and windows, which can create drafts or impede them, to the location of the hayloft doors in relation to a particular horse’s stall can affect the quality of air a horse breathes,” says Lascola.

When the horse is kept at a boarding facility, implementing environmental changes requires cooperation of the staff there.

“Communication is key,” she says. It is important to make sure that changes owners and veterinarians have requested are implemented by all barn hands and workers on the property.

Work with Your Veterinarian

“The most important aspect of monitoring and controlling air quality is working with the horse’s primary veterinarian and the owners as a team,” says Lascola. “We always want to try environmental modifications before we jump to drug treatments, because often horses with heaves and IAD can be managed by just changing their surroundings which is both less expensive and less time consuming for the owner.”

Bronchodilators and steroids like those used to treat human asthma can also be prescribed for horses that do not respond to management alone. Bronchodilators should be used primarily as a rescue therapy when the horse is showing signs of more labored breathing, while steroids are used to treat the underlying inflammation in the lung. These medications can be administered orally or with intramuscular or intravenous injections and are also available as inhalers. Horses tolerate these treatments very well but, given their cost, especially for inhaled medications, addressing environmental changes is the best first step.

All of the recommended measures are designed to improve the horse’s quality of life. While some horses will need medication in addition to environmental changes, the key is to figure out which interventions are working, and keep up with them over the long term so that the horses’ breathing troubles do not return.

Reprinted with permission from the University of Illinois College of Veterinary Medicine.  

How to Set Up an Equine Disease Isolation Unit on Your Farm

An effective isolation area can help contain an infectious disease outbreak. Here’s what you need to know
horse isolation

If your horse contracts an infectious disease, it’s critical that you isolate him from other horses to prevent the spread of infection. It is also important to prevent indirect exposure, such as when people handling an infected horse spread the pathogen to other horses via physical contact and equipment sharing.

Isolation requirements vary based on the infectious agent. For controlling some infections isolation can be as simple as stall confinement, if the stall is secure and the horse is not able to reach horses that walk by or are housed next to him.   

But if a horse has a fever and neurologic signs consistent with equine herpesvirus-1 infection, for instance, he might be carrying high levels of the virus and become a primary source of spread. Work with your veterinarian to move the horse to an alternate facility or isolated area.  

Restrict the movement of (i.e., confine to a barn, part of a barn, or area) any horses that were kept adjacent to the infected and now isolated patient, and take their temperatures twice daily until a veterinarian determines the nature of the infection. Institute a quarantine of that focal area, and limit access to and from it. Exercise horses housed there only when uninfected horses are not in the area.

An effective isolation barn has these characteristics:

  • It is well-separated from other barns and horse traffic.
  • It can be cordoned off to control human traffic in and out of the area.
  • Horses stalled adjacent to each other cannot directly contact one another.
  • It has cleanable nonporous surfaces, including walls and flooring (mats). Use liquid laundry detergent mixed with water for cleaning stalls (this is also useful for cleaning trailers). A 10% bleach solution is a good general disinfectant. Keep in mind that organic material and direct sunlight inactivate bleach. Discuss safe disinfectant use, including dilution, with your veterinarian. The disinfectant choice and use might vary based on the infectious agent at hand.
  • It is reserved only for use by those horses suspected as infected and not by other horses at any time.
  • It has disinfectable water buckets and feeders and separate equipment (wheelbarrows, pitchforks, etc.) used only in the isolation barn and disinfected after use.
  • It has a sink for hand-washing and a treatment area. Reserve space for storing items needed for biosecurity, such as gloves, disposable coveralls, boots, disinfectant, footbath stations (plastic tubs), and separate garbage collection. Convert a stall into a storage area during an outbreak, if needed.

The length of the movement-restriction period depends on whether other horses on the property develop a fever during the next seven to 10 days. Quarantine can be lifted after the last horse to develop fever or clinical signs is disease-free, as confirmed by your veterinarian.

Equipment needed to set up an effective quarantine area includes:

  • Treatment carts;
  • Painters’ disposable coveralls;
  • Disposable gloves;
  • Rubber boots;
  • Foot bath containers;
  • Garbage bags;
  • Garbage cans with secure lids;
  • Disposable plastic shoe covers;
  • Dedicated thermometer for each horse;
  • Dedicated equipment for each horse; and
  • Appropriate signage.  

Anyone entering the isolation barn should follow appropriate sanitation measures, including:

  • Wearing rubber boots dipped in a prescribed foot bath and/or disposable booties.
  • Using disposable or dedicated gowns or coveralls for each horse stall.
  • Changing disposable gloves between handling each horse.
  • Wearing a treatment coat over the reusable coveralls.
  • Showering or changing clothes before touching other horses if contaminated while treating an infected horse.
  • Washing hands for 60 seconds (or singing “Happy Birthday” twice at normal tempo) before entering or leaving the isolation area. Using disposable towels and depositing them in a covered waste container at the hand-washing site.
  • Setting up a perimeter around the stall area to limit entry and traffic. You can designate this perimeter with ropes, construction fencing, and so forth. Restrict random access to this area, and provide only one entry and exit.
  • Installing appropriate lighting for easier assessment and treatment.

Adopting this equipment and these methods can mean the difference between an extended outbreak with multiple cases and one that is brought to conclusion expediently.

Bit Type, Bridle Style Impact Rein Tension

Which setup results in the least rein tension: Western curb bits or English snaffle bits?

The answer might surprise you.

In a recent study, researchers in Germany determined that Western curb bits caused less rein tension than did English snaffles. They also found that one-handed riding is associated with more stable rein tension.

“We furthermore determined that rein tension was actually higher with bridles that prohibit jaw-opening, indicating possible welfare issues,” said Sandra Kuhnke, PhD candidate at the University of Kassel, on behalf of herself and Uta König von Borstel, PhD, also of the University of Kassel. Kuhnke presented their study at the 2017 International Society for Equitation Science conference, held Nov. 22-26 in Wagga Wagga, Australia.

Kuhnke and von Borstel investigated the effects of various bridles, bits, riding styles, and horses’ muscle trigger points on rein tension. Muscle trigger points are “irritable” spots on the horse’s body within the fascia (connective tissue that surrounds muscles and muscle groups), Kuhnke said. The researchers measured study horses’ reactions to them touching about 25 trigger points on both sides of the body, scoring horses’ reactivity levels at each point. The results give a reliable gauge of muscle condition, she said.

To test rein tension and stability, they used rein tension meters on nearly 100 horses ridden in curb bits or snaffle bits, two-handed or one-handed, Western or English.

They found that, generally, snaffle bits were associated with higher rein tension than curb bits. However, the bit-bridle combination had a significant effect on the tension. For example, a bridle with a plain noseband and curb bit resulted in the lowest average rein tension in the whole study.

As far as snaffle bits go, rein tension was lowest when combined with a figure-eight noseband. It was highest with a flash noseband—nearly three times as high as with a figure-eight, Kuhnke said. Still, the lowest average snaffle bit rein tension was almost twice as high as it was for the lowest average curb bit tension.

When riders rode one-handed, their rein tension was more stable than when riding double-handed, she said. And it was even more stable when right-handed riders rode with their left hand only.

Meanwhile, riders with better rein tension stability had horses with more symmetric trigger point reactions (similar on both sides), Kuhnke said. It could be that the horse’s muscular condition affected the rein tension, as well as the other way around, she added.

“Considering relationships between horses’ muscular condition and rein tension appears important for equine welfare and has the potential to add further knowledge to investigations of horse-rider interactions,” Kuhnke said

Equine Ringbone: Process, Progress, and Prognosis

Equine Ringbone: Process, Progress, and Prognosis

How veterinarians and farriers manage this degenerative arthritic condition

We’ve all been there: We wake up on our day off, which also happens to be the first day we’ve seen the sun in a week. Excitedly, we head out to the barn to tack up for a ride and, instead, find our horse favoring a foot.

Let’s say in this instance, upon closer examination, we notice heat and swelling just above the hoof or, perhaps, even a bony lump. What’s the next step—call the farrier, or call the veterinarian?

The answer is both. As it turns out, veterinarian, farrier, and owner form the optimal team to determine a treatment plan for hoof-associated issues, especially if your horse’s clinical signs lead to a ringbone diagnosis.

“I’m a huge proponent of the team approach to treating ringbone or any hoof-related problem: the owner; the veterinarian, who provides the medical and diagnostic expertise; and the farrier, who offers in-depth insight on shoeing and the mechanical forces of concussion,” says Vern Dryden, DVM, CJF, of Bur Oak Veterinary and Podiatry Services, based in Lexington, Kentucky.

Read on to learn what ringbone is, how your team can work together to diagnose and treat it, and what your horse’s prognosis is if he has it.

The What and How of Ringbone

Ringbone, defined simply as progressive arthritic change that affects the pastern and/or coffin joints (high and low ringbone, respectively), can occur in one or multiple limbs. Although pain from joint inflammation (arthritis) and an immune system on overdrive initially cause the lameness, eventually a bony buildup (hence, the term ringbone) can fuse the joint and relieve it.

Predisposing and contributing factors include conformation, excessive weight, and use. “Horses with extremely upright pasterns or that tend to have an extreme variation, either a valgus (a limb deviating outward from midline) or varus (deviating inward) deformity where they’re collapsing one side of the joint space, can lead to arthritic changes,” says Dryden. “And long-term excessive weight can at least exacerbate these issues once a horse has ringbone. But the most common causes are working on hard surfaces from a young age and injuries to the joint’s cartilage and/or ligaments that lead to osteoarthritic changes in the joint.”

“Most of the cases I see are in middle-aged to older horses,” says Stephanie Caston, DVM, Dipl. ACVS-LA, an assistant professor at Iowa State University, who has studied the use of alcohol injections to fuse arthritic pastern joints (read about it at TheHorse.com/27004). “We see everything from Warmbloods to Quarter Horses and everything in between. I can’t think of one breed or discipline that’s more predisposed to it. I do see some younger horses with ringbone, but like with people, arthritis is usually associated with wear and tear on joints, so it takes some time to develop.”

If your horse’s conformation lends itself to developing ringbone, Dryden suggests avoiding heavy or constant work on hard surfaces and shoeing to improve any structural deficiencies. “There are many different ways to approach it,” he says. “You might want to use pads between the hoof and the shoe to decrease the vibratory forces and concussion or use a synthetic shoe.” As with any health–related condition, your veterinarian can best assess your particular horse’s needs.

Vet watching horse jog

The Diagnostic Process

When your veterinarian arrives to determine the cause of your horse’s ­lameness, he or she will begin with a thorough physical exam, including taking vital signs (temperature, pulse, and respiration) and inspecting the limbs visually and manually for heat, swelling, and a digital pulse. “Horses with ringbone will often have that telltale firm, bony swelling around the ankle area,” says Caston. However, adds Dryden, often you’ll notice lameness before bony proliferation ­occurs.

After the physical exam, your veterinarian will watch the horse’s gait while you or an assistant jogs him, before and after flexing the lower limb to move the coffin, pastern, and fetlock joints (called a flexion test). “It’s very difficult to isolate among those three, but if the horse becomes more lame at that point, you’ll know you’ve at least isolated the lameness to that general area,” Dryden says.

Your veterinarian will follow up by blocking certain nerves (systematically injecting them with anesthetic until pain is eliminated) to pin down the origin of pain more closely. “I’d start with a palmar digital nerve block that would typically block (pain and lameness in) the heels and most of the foot,” says Dryden. “But in many cases, that’s going to block some of the pastern region, as well, due to diffusion of the anesthetic. I’d follow that up with an abaxial nerve block, which is placed at the base of the proximal sesamoid bones (located at the back of the fetlock) to numb the structures below the fetlock and which often blocks some of the fetlock, as well.”

Dryden says that if nerve blocks and pastern swelling indicate something significant there, he’d follow up with radiographs.

“In some cases,” he adds, “the blocking pattern makes it difficult to localize the lameness, so I might also do an intra-articular (anesthetic injected directly into the joint) block. If that blocks out within a short time, then that’s a very, very, very definitive diagnosis that the problem is within that pastern joint.

“At that point,” he says, “we’d go to radiographs to see if there are any osteoproliferative (bone-deposit-forming) changes or minimization of the joint space.”

“It’s pretty easy to identify those changes associated with arthritis on the films,” adds Caston. “Most of the time, diagnostics will consist of X rays. But if we don’t get an answer with X rays, we can do MRI, bone scans (aka nuclear scintigraphy), or ultrasound. Unless it’s a very early case, you probably wouldn’t have to go to those advanced imaging methods.”

Once your veterinarian determines the exact location and degree of the horse’s ringbone, he or she will discuss treatment options with you.

Xray of high ringbone

Shoeing Techniques

Ringbone is a chronic degenerative condition, so rest will not resolve it. “In fact,” says Caston, “it may even make your horse more sore, especially if he’s cooped up in a stall where he can’t exercise freely and so may get stiff or gain weight.”

After diagnosis your veterinarian and farrier can consult to come up with shoeing options for your horse. Although special shoeing won’t cure or halt ringbone, Dryden says it can slow the progression by preventing excessive joint movement and, thereby, keep your horse more ­comfortable.

Paying close attention to hoof angles can help. “A hoof angle that’s excessively upright or excessively low can be problematic for these cases,” Dryden says. “An upright hoof capsule doesn’t absorb concussion well and transmits vibratory forces up the limb. When angles are too low, it’s hard to create a nice alignment with your horse’s bony column (the coffin and pastern bones).”

He adds that shoes for horses with ringbone should promote easy breakover (the moment the heels lift off the ground). “We can reduce mechanical leverage on the joint space by bringing the breakover back toward the center of the foot,” he says. “One of the old shoeing prescriptions I used 20 years ago was to take a shoe, shape it to the foot, and then take another shoe a size or two smaller and weld it in the center to create a sort of step, which made it easier for the hoof to break over and reduced torque on the joint.”

Now, he says, in addition to this and other techniques farriers use with similar goals, some aluminum shoes have an aggressive breakover built into them to reduce leverage.

Just as better breakover can help, so can minimizing concussion during shoeing. “Farriers will notice when they go to nail a shoe onto these horses that the horse definitely doesn’t like the process,” Dryden says. “They get irritable because they’re anticipating that hammering. So changing the shoe to minimize concussion is very logical. Adding a plastic or rubber pad between the shoe and foot or a silicone or polyurethane pad also helps reduce concussion. Or you can go to the other end of the shoeing protocol spectrum and use synthetic glue-on shoes that don’t need any hammering.”

Medical Management

Pain relief is front and center when treating horses with ringbone, and non-steroidal anti-inflammatories (NSAIDs) often provide the first line of defense. The most commonly used are phenylbutazone (Bute), flunixin meglumine (Banamine and others), ketoprofen (Ketofen and others), and firocoxib (including Equioxx).

“Any of these typically will help a horse with arthritis be more comfortable,” says Caston. “Most people are going to be using Bute. It’s the most common, it’s cheap, it’s readily bioavailable to the horse, and has good distribution (to the digit).”

Dryden adds that in the short term Bute is great, but for the long term he prefers firocoxib. “It’s easier on the horse’s gut because of its ability to selectively inhibit certain cyclooxygenases (COX, a type of enzyme) for prostaglandin (a pro-inflammatory molecule) release, whereas Bute is nonselective for COX inhibitors; it inhibits all of them,” he says.

In a nutshell, it’s best not to inhibit all COX enzymes—some perform important gastrointestinal functions, and doing so could cause gastrointestinal upset. For more on this, see TheHorse.com/27043.)

Just as they can for other osteoarthritic conditions, chondroprotective (joint protective) agents such as glucosamine and chondroitin sulfate, which veterinarians and owners administer orally, can help improve affected horses’ comfort.

“Early on at the diagnosis of any arthritic condition, we’ll often prescribe these, and in some cases owners already have their horses on a supplement containing these substances for ­maintenance—especially older horses,” says Caston. “They may help with the health of other joints, as well, and for the horse’s comfort overall. But for a horse whose joint is fused, they won’t do anything to help that joint.”

Hyaluronic acid (HA), which veterinarians can administer intravenously or by intra-articular injection, is another chondroprotective supplement. “HA and corticosteroids are probably the most commonly used (injections) to treat these horses and help reduce inflammation in the joint,” Dryden says.

“HA is a building block of some of these components of the joint—cartilage and fluid—with some anti-inflammatory effects of its own,” says Caston. “Early on in the diagnosis, if we’re treating medically, we may combine corticosteroids (cortisone) with an HA product. It’s been shown to improve cartilage and joint health.”

Polysulfated glycosaminoglycan (PSGAG) is another medical treatment that can supplement your horse’s naturally occurring joint fluid and cartilage components. “PSGAGs that preserve the integrity of the joint are critical in managing ringbone,” says Dryden. “You can manage symptomatically with injections of HA and steroids, mainly to give the horse relief, but that doesn’t necessarily stop or prevent the disease process from occurring. There’s been virtually nothing that we’ve been able to do to completely halt the disease.

“I do think that in some cases, when you have some bone pain associated with ringbone, that bisphosphonates on the market can be helpful,” he adds. “They reduce osteoclast (bone breakdown) activity, and that essentially reduces bone remodeling. Additionally, these bisphosphonates have some analgesic effect for bone pain to keep these horses ­comfortable.”

Regenerative Treatments

One biologic Dryden says has merit is interleukin-1 receptor antagonist protein (IRAP). This is an anti-inflammatory therapy that blocks interleukin-1—one of the major inflammatory substances the body releases in the event of injury—from causing inflammation. “It’s helpful in treating some of these arthritic cases that are refractory (do not respond) to steroid treatment, so it’s another tool we have to help manage these cases from an intra-articular standpoint,” he says. “There’s another product on the market called Pro-Stride that I’ve used, which is a combination of PRP and IRAP. It’s an intra-articular injection that (in my experience) seems to have merit in some of these arthritic joints.

“Veterinarians are using PRP (platelet-reduced or -rich plasma) and stem cell therapies in these horses,” he continues. “I’d say there’s not enough literature out to say how well they work for severely arthritic joints, but I’d say it’s important to note that people are trying them.”

IRAP, stem cells, and PRP can all be used, generally earlier on in treatment, in a joint that’s arthritic or injured,” says Caston. “They vary a little, but the goal for all three is to help reduce inflammation within the joint. PRP and stem cells have growth factors that help with repair. All come with different costs and, thus, may play into owners’ decisions on whether they’re going to choose those products.”

Can My Horse Continue Working?

Ringbone will affect your horse’s ability to work. Dryden says that on a scale of one to five in severity, horses can be managed and compete up to about a two. Beyond that, due to pain, the horse is not likely to compete at a high athletic level. Horses at a range of three to three-and-a-half can be very lightly used and from four to five are severely lame at a walk and unusable until the joint fuses fully.

Xray of gelding with high ringbone, surgical arthrodesis

Sometimes the horse’s body fuses the joint on its own (called ankylosis). Or, your veterinarian can fuse the joint in one of two ways. The preferred method is surgery to screw on a plate that stabilizes the joint. But if, for whatever reason, surgery is not recommended for your horse, your veterinarian can inject the joint with one of several substances that will degrade the cartilage and allow the horse’s body to finish the fusion process.

In her research, Caston monitored the success of injecting ringbone-affected pastern joints with alcohol rather than traditionally used but harsher chemicals with more side effects, especially if they get under the skin or leak out of the joint.

This injection method is less expensive than surgery, which is one reason owners choose it. Another is that some horses have other conditions, such as navicular disease or arthritis elsewhere, to manage at a cost that precludes surgery.

The good news is once the joint fuses, the horse can return to work. “That’s the goal, and that’s why this is such a special joint,” says Caston. “There are joints we fuse and the horse can become breeding-sound or pasture-sound, but with a pastern, because successfully fusing that joint doesn’t affect the motion of the limb, they can go back to full athletic ability.

“Owners and veterinarians often choose shoeing, medical treatments, and/or regenerative options prior to making the decision to pursue fusion of the joint because of cost and possible side effects and complications from either surgery or alcohol-facilitated ankylosis,” she continues. “With any procedure there are risks, and although the risk for complications may be low, if more conservative methods keep the horse comfortable and in work, then it makes sense to continue with those methods prior to pursuing surgery or facilitated ankylosis. When those treatments no longer keep the horse comfortable enough to be ridden or to be comfortable in pasture, then fusion of the joint is recommended.”

Take-Home Message

In the short term, ringbone can be painfully debilitating for your horse. However, once the pastern joint has fused, either on its own or with the help of surgery or injection, most horses can return to full activity. But this isn’t the case with the high-motion coffin joint. Even if you fuse it, says Caston, horses are usually only comfortable enough to be pasture sound.

In the meantime, a variety of treatments, from shoeing techniques to medical approaches to regenerative therapies, can help ease your horse’s pain.

Your treatment team—you, your farrier, and your veterinarian—can evaluate your horse’s unique situation and formulate a course of treatment that’s best for you both.

About The Author

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Diane E. Rice earned a bachelor’s degree in agricultural journalism from the University of Wisconsin, then melded her education and her lifelong passion for horses in an editorial position at Appaloosa Journal. She currently works as a freelance writer, editor, proofreader, and photographer and has served on American Horse Publications’ board of directors. Rice spends her spare time gardening, reading, serving in her church, and with her daughters, grandchildren, and pets.

5 Tips for Feeding Lactating Mares

Lactating mares’ nutritional requirements increase drastically in order to maintain weight while providing nursing foals with enough critical nutrients.
lactating mare

Do you get tired just watching your new foal gallop around his pasture? Try supplying him with enough energy and nutrition to allow him to frolic and play all day! Lactation is one of the most physiologically demanding stages for broodmares. Their nutritional requirements increase drastically in order to maintain weight while providing nursing foals with enough critical nutrients.

Lactating mares have the highest nutrient requirements during the first three months of lactation. These requirements decrease as their milk production decreases—in both quantity and quality—during the fourth through sixth months post-foaling.

If a lactating mare’s diet is restricted, she will sacrifice her own calorie, protein, and mineral stores for milk production. In severe cases an undernourished broodmare can suffer weight, muscle tone, and bone loss. Thus, it’s crucial to provide lactating mares with enough feed to sustain both themselves and their growing foals. Here are five tips for meeting mares’ nutritional needs during lactation.

 Go with grain.

Although high-quality hay and/or grass should remain the basis of the diet, in most cases forage alone cannot meet lactating mares’ nutritional requirements. Grain products formulated for broodmares are designed to meet pregnant and lactating mares’ nutritional needs. Follow the feeding rates suggested on the tag or bag corresponding to the month of lactation.

Split it up.

Many mares in the first three months of lactation will require between 10 to 15 pounds of a commercial grain mix per day to meet their increased nutrient requirements. Dividing this into two or three meals per day can help reduce the risk of digestive upset and increase nutrient digestion and absorption.

Include ‘building blocks.’

High-quality protein is vital to delivering essential amino acids to the foal. Thus, the mare’s dietary requirements for lysine, the first limiting amino acid in growth and development, increase from about 38 grams per day in late pregnancy to 85 grams per day in early lactation for an average 1,100 pound mare. When choosing a grain mix, check the feed tag and ingredient list to ensure they include guaranteed levels of lysine.

Watch for food thieves!

Most foals will begin to nibble on their mare’s grain within weeks of birth and can easily consume up to four pounds each day by the time weaning approaches. You might need to increase the amount of grain you provide your mare each day to ensure she is still getting enough to meet her needs. Otherwise, consider raising her feed tubs higher than the foal’s reach or providing creep feed for the foal.

Monitor body condition score.

Monitor a lactating mare’s body condition frequently, and adjust her diet as needed. Aim to maintain pregnant and lactating mares at a body condition score of 6 to 7, and never less than 5, on the 1-9 Henneke scale. Should a mare’s body condition drop substantially, her reproductive performance (for example, cycles per conception) might decrease.

Take-Home Message

Lactating mares have drastically increased nutritional requirements in order to keep themselves and their foals healthy. Ensuring that your broodmare consumes enough calories each day will help foals start out on the right foot and help keep mares’ bodies functioning optimally.

About The Author

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Kristen M. Janicki, a lifelong horsewoman, was born and raised in the suburbs of Chicago. She received her Bachelor of Science degree in Animal Sciences from the attend the University of Illinois at Urbana-Champaign and later attended graduate school at the University of Kentucky, studying under Dr. Laurie Lawrence in the area of Equine Nutrition. Kristen began her current position as a performance horse nutritionist for Mars Horsecare, US, Inc., and Buckeye Nutrition, in 2010. Her job entails evaluating and improving the performance of the sport horse through proper nutrition.