How Sensitive Is Your Horse’s Face? New Tools Can Tell You

Researchers measured horses’ facial sensitivity to touch, pressure, and heat. The results could help diagnose cases of equine idiopathic headshaking and improve welfare.

How Sensitive is Your Horse’s Face? New Tools Can Tell You
He shakes off tiny flies and gnats that land on his nostrils, so you know your horse has a sensitive face. But how sensitive, exactly? 

Researchers measured horses’ facial sensitivity to touch, pressure, and heat to find out what they’re feeling. They used handheld devices—including a pressure reader designed for horse faces—to check each horse’s sensitivity and facial nerve functions.

“Knowing the normal sensitivity values of the face would provide a tool for veterinarians to diagnose alterations in sensitivity,” said Kata O. Veres-Nyéki, DrMedVet, Dipl. ECVAA, PhD, MRCVS, of The Royal Veterinary College, in Hatfield, the U.K., formerly of the Vetsuisse Faculty at the University of Bern, in Switzerland.

“Acute injuries of the face are probably obvious, but chronic pain conditions might be overlooked otherwise,” Veres-Nyéki said. “Using the quantitative sensory testing methods, we can not only detect alterations but also follow up the efficacy of analgesic (pain relief) treatments in a noninvasive (harmless) way.”

Testing Touch, Pressure, and Heat Thresholds in Equine Faces

Veres-Nyéki and her fellow researchers tested facial sensitivity in 34 healthy Warmblood mares, geldings, and stallions ranging in age from 1 to 23 years old. They used von Frey filaments—a kind of thin, flexible stick—to test tactile thresholds (how sensitive horses are to light touch such as from a hair or a fly). To test heat thresholds, they pressed a handheld thermode (medical heating device) gently against the horse’s facial skin. The temperature gradually increased from 30 degrees C (86 degress F) up to a maximum of 55 degrees C (141 degrees F). And to test pressure thresholds, they developed a handheld algometer with a silicon tip that applies gradually increasing pressure against the horse’s face.

In all three tests, the horses were free to move their heads, and the test stopped when the horse reacted in any way to the contact (such as by moving the head away, twitching the skin, or blinking reactively), Veres-Nyéki said.

Comparing to Humans, Other Horses

Horses seem slightly less sensitive than humans when it comes to facial contact, the researchers reported. But Veres-Nyéki explained that this might be because humans can say when they feel the sensation, whereas horses must physically react to the stimulus—which might mean they feel it and tolerate it before reacting.

And although men have higher thresholds than women for pressure and heat, sex didn’t seem to affect sensitivity thresholds in horses.

Age, however, did. Veres-Nyéki said horses generally had increasingly higher thresholds for all three kinds of contact—touch, pressure, and heat—as they got older. “It is not known why would that happen, but it is suspected to be caused by decreased innervation density (basically, the age-related ‘damage’ of the nervous system),” she said.

Pinpointing Facial Regions to Diagnose Headshaking

The study allowed the scientists to pinpoint precise places on the horse’s face for the most reliable results of each test. Specifically, they recommended testing tactile sensitivity on the nostril, pressure sensitivity at the temporomandibular joint (on each side of the jaw), and heat sensitivity at the supraorbital foramen (the forehead just over the eye). These sites gave the most consistent results and are innervated by the trigeminal nerve, she said.

Facial sensitivity testing of individual horses might help diagnose, in particular, cases of equine idiopathic headshaking, a neuropathic pain condition, Veres-Nyéki said. By performing these field tests and comparing measurements with the healthy horse threshold data provided in the researchers’ open-access study, veterinarians can detect possible facial nerve sensory abnormalities, she said.

Keeping Facial Sensitivity in Mind

Clipping facial hair for testing isn’t necessary, as the team’s results showed only insignificant differences when testing sites were shaved versus unshaved. Even so, the scientists did note trends suggesting that unshaven horses were more sensitive to touch, underlining the importance of leaving clipping horses unclipped (except when medically necessary) so as to not deprive them of their full level of sensitivity.

The study has practical applications in equitation, as well, Veres-Nyéki added. For example, trainers might consider using gentler equipment on younger horses due to their lower sensitivity thresholds.

“The equipment used on the face should not provoke pain in the first place, but as more force is applied to them over smaller surfaces, they might cause pain in the horses,” she said.

About The Author

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Passionate about horses and science from the time she was riding her first Shetland Pony in Texas, Christa Lesté-Lasserre writes about scientific research that contributes to a better understanding of all equids. After undergrad studies in science, journalism, and literature, she received a master’s degree in creative writing. Now based in France, she aims to present the most fascinating aspect of equine science: the story it creates. Follow Lesté-Lasserre on Twitter @christalestelas.

Equine Physical Therapy Must Be Individualized

Biomechanics expert: The wrong rehab program for a horse can be counterproductive.

 

Equine Physical Therapy Must Be Individualized
Physiotherapy can improve muscle development and help rehabilitate horses recovering from pain or injury. However, developing a custom program for each horse’s unique situation is critical to prevent stimulating the wrong movement patterns, said one equine biomechanics expert. 

“It’s important to be knowledgeable about what you’re doing with physiotherapy exercises and select appropriately for each horse at each stage of his development,” said Rachel Murray, MA, VetMB, MS, PhD, MRCVS, Dipl. ACVS, Assoc ECVDI, an orthopedic specialist at Rossdales Equine Hospital, in Newmarket, U.K. She spoke on the topic during the Centaur Biomechanics Virtual Equine Sports Science Summit on Oct. 3.

Stable (core) exercises, groundwork, ridden exercises, dry and water treadmill work, swimming, and even changes in management (turnout, feeding height, etc.) can lead to major improvements in a horse’s musculature, comfort, and performance—so long as you take individual aspects into consideration, Murray said.

Each exercise must be adjusted to each horse, she said. That means selecting the right muscles to activate by hand or electrical stimulation, as well as choosing the right placement of training aids such as elastic bands. It also means accurately determining ground pole height and spacing, treadmill water height, treadmill speed, and more for each horse at each stage of his development.

Different horses have different genetics and life histories that can lead them to use their bodies in different ways, said Murray. As a result, one horse won’t necessarily move the same way as another performing the same kinds of physiotherapy exercises. In some cases the exercises—if not adapted to the horse—could accentuate musculoskeletal or neurologic problems or create new ones. Specifically, they could create the wrong movement patterns, leading to weakness and/or pain in different areas of the body and poor performance.

“You really have to look at the individual patient,” Murray said.

Horses have different levels of stability and flexibility in different areas of their body, she said. For example, one might be very flexible in the lumbosacral (lower back) region but very unstable—meaning he might shift his weight during certain core exercises instead of developing the target muscle. Horses who are stiff in the lumbosacral region might overflex their hocks and stifles during groundwork over poles instead of flexing the back. And horses with instability in the hind limbs—which is surprisingly common, she said—might rotate their hocks too much during exercises involving turns instead of strengthening their hindquarters.

Even natural stance can make a difference, she explained. For instance, horses should ideally eat from the ground for good back and neck musculature. But a horse that always keeps one forelimb standing far beneath him while eating from the ground might develop an asymmetry under saddle. In that case, feeding him from a haynet at shoulder height could be a better solution if it keeps his front feet more even, said Murray.

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Passionate about horses and science from the time she was riding her first Shetland Pony in Texas, Christa Lesté-Lasserre writes about scientific research that contributes to a better understanding of all equids. After undergrad studies in science, journalism, and literature, she received a master’s degree in creative writing. Now based in France, she aims to present the most fascinating aspect of equine science: the story it creates. Follow Lesté-Lasserre on Twitter @christalestelas.

7 Dietary Deficiencies in Horses

Providing a balanced diet that meets your horse’s nutritional needs and being aware of possible shortcomings are vital for his care. Read about seven aspects of your horse’s diet that might not be up to par in this excerpt from the November 2020 issue of The Horse.

 

7 Dietary Deficiencies in Horses

Deviating from horses’ core nutritional needs can adversely affect health

Horses have specific nutritional needs for water, energy, protein, minerals, and vitamins. While high-quality forage (pasture and hay) and, if needed, a commercial feed or ration balancer can easily meet these requirements, deficiencies in the equine diet do still occur. They often depend on the age and type of horse, as well as the geographic region. Providing a balanced diet that meets your horse’s nutritional needs and being aware of possible shortcomings are vital for his care.

We’ll describe seven aspects of your horse’s diet that might not be up to par.

Horse owners don’t often consider water to be a commonly deficient nutrient, but when it’s unavailable or of poor quality, it can lead to a life-threatening insufficiency. Jessica Leatherwood, MS, PhD, assistant professor of equine science in Texas A&M University’s Department of Animal Science, in College Station, says dehydration often occurs in winter, when water is extremely cold or covered in ice.

“Horses typically will drink less if they are cold and offered cold water,” she says. “Less water consumption coupled with increased forage intake to stay warm predisposes the horse to dehydration and possible impaction colic.”

Dehydration also puts horses at risk for impaired muscle and nerve function and reduces their ability to regulate their internal temperature. Leatherwood encourages owners to combat this by offering warm water during cold months and by ensuring ice does not cover troughs or waterers.

Horses can also become dehydrated during and after performing intense exercise, especially if they’ve sweated profusely due to heat and humidity. Lack of water intake during travel is another concern.

In hot, humid conditions or when traveling, some horse owners opt to add electrolytes, which include the minerals sodium, potassium, chloride, calcium, and magnesium. These additives mask changes in water sources so horses will be more inclined to drink. If you choose to add electrolytes, it’s important to do so in advance of travel, exercise, or the onset of other conditions that might contribute to dehydration because, initially, your horse might drink less because of the unfamiliar taste. You can also give electrolytes as an oral paste, leaving the water unchanged and, therefore, not limiting its consumption. This leads us to our next deficiency. This article continues in the November 2020 issue of The Horse: Your Guide to Equine Health Care. Subscribe now and get an immediate download of the issue to continue reading. Current magazine subscribers can access the digital edition here. 

Chelsie J. Huseman, MS, PhD, is an assistant professor and extension horse specialist in Texas A&M University’s College of Agriculture and Life Sciences, in College Station. Her role as a horse specialist is to serve the state of Texas by designing and implementing educational programming and resources for adults and youth within the horse industry.

A Quick List to Help Prepare Your Horses for Winter

From nutrition considerations to preventing mud, it’s time to get ready for winter.

A Quick List to Help Prepare Your Horses for Winter
Growing up in the United Kingdom, late summer and early fall were the times when  the hay barn was filled with enough of that year’s harvest to get us through the winter. Once we had filled the barn, we always had a sense of relief and a feeling that we were ready for whatever winter might bring. It was a time of year to look ahead to winter and make necessary preparations. Now I live in Arizona. Some would hardly consider our state as having a “winter,” but we do drop 60-plus degrees Fahrenheit from summer temperatures, so some preparation is still necessary. 

In no particular order, here are a few of the things I have been thinking about that you might want to put on your getting-ready-for-winter checklist.

Assess your horse’s condition.

Too fat or too thin? If too fat, then winter can be your friend. Cooler temperatures can result in weight loss, even without reducing feed intake, which is ideal. Skip that blanket, and let your overweight horse burn some calories producing heat to stay warm. If your horse is on the thin side, then try to put pounds on him before winter sets in and weight gain becomes harder. Assess the possible cause of weight loss. It’s always a sign that your horse’s calorie level is inadequate. You might already be feeding a lot, but those calories aren’t getting to their destination. Ask yourself why, and what else is going on. Have your veterinarian assess the horse to rule out dental issues, internal parasites, and pain, which can all cause weight loss. Is the horse being bullied in pasture and kept away from hay? Maybe he’s a hard-keeper and needs more than just hay? Perhaps he needs digestive tract support to facilitate hindgut fermentation and better use the forage in his diet? Consider working with a qualified equine nutritionist who can suggest ways to best support weight gain.

If you ride more in the summer than winter and will be letting horses down, now is a good time to send in tack for repairs, such as stirrup leather restitching or saddle billet replacement. If you won’t be using an item for a few months, condition it and put it in storage. If you ride more in the winter, take equipment out of storage and prepare them for use.

Service clippers and blades.

If you will be body-clipping this winter (and you didn’t do this at the end of last winter), send your clippers to be serviced and blades sharpened. It will make for a much more pleasant job, and your horse will appreciate clippers that run cool and blades that cut well.

Check blanket fit/search for preseason sales.

If you are clipping, you will likely be blanketing. Depending on the weather, you might need to blanket even if your horse is unclipped. Keep in mind that many of us overblanket. Educate yourself on good blanket selection for your climate. Make sure existing blankets still fit, as sometimes blanket fit changes as horses gain or lose weight. If you need something new, now is a great time to hit preseason sales. Mend any blankets you didn’t get mended last year, and consider buying spare leg straps and a rip repair kit so you can keep your blankets functioning through the season. If you live in a dry climate, have static guard (available from the laundry aisle) on hand.

Be weather ready.

If you live in a wet climate, prepare now for mud. If your horses get turned out, what area will you make your sacrifice area? Consider placing fine gravel in heavy-traffic areas such as gateways and around water troughs. Check with local clean water agencies and university extension offices, as they often have excellent resources and help that is appropriate for your area. If you live in a region that gest snow and ice, stock up on vegetable shortening to pack in to hooves to prevent ice balls from forming during turnout. Keep it somewhere where it will be warm enough to scoop out of the container!

Check lights.

Discovering in the dark on a cold night that a bulb has burned out is frustrating. Many of us do not use our barn lights in the summer, so now is a good time to make sure all circuits are working.

Assess pasture condition.

Do your pastures need to be reseeded, harrowed, rolled, or mowed before being shut down for the winter? Now is the time to get out and do those tasks while you can still get machinery into pastures without damaging them.

Buy an electric kettle for your tack room.

Great for defrosting frozen facets and making hot cocoa, every tack room should have one! Unplug it when not in use.

Check trough heaters and buckets.

For those in colder climates where frozen buckets and troughs are issues, check existing bucket and trough heaters to make sure they work. Consider purchasing if you do not have these already, or look online for ways to insulate water troughs and keep them from freezing without the need for electricity. If using electric heaters, be certain your horse will not get shocked while drinking.

Lag pipes.

Nobody enjoys frozen or, worse, broken pipes. Insulate them as well as possible. Have a plan for what you will do if your water supply does freeze. How will you get water to your horses?

Feed salt.

f you do not do so already, add 1 tablespoon of salt per 500 pounds of body weight to your horse’s ration, and provide an additional salt source. As the weather fluctuates through fall into winter, many horses do not drink as much. Add to that the transition from pasture to dry hay and reduced movement once stalled, and it becomes obvious why incidences of colic increase as we go into winter. Keeping your horses drinking is a great insurance against impaction colic, and salt will help encourage them to drink.

Whether we like it or not—and in Arizona I admit we like it—winter is coming. Take the time now to be prepared.

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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.

Abrupt Diet Changes’ Effects on the Equine Microbiome

Researchers say progressive changes in diets lead to healthier microbiomes and fewer digestive issues, such as diarrhea and colic.

Abrupt Diet Changes’ Effects on the Equine Microbiome
A rapid switch between grass pasture and a hay diet can upset the gut microbiome, which might explain why some horses experience colic or laminitis when changing feeding regimes, according to Scottish researchers. 

While scientists still don’t fully understand the ideal health status of horses’ gut microbiomes—the ecosystem of microscopic organisms such as bacteria and viruses inhabiting the digestive system—they do recognize that changes in the microbiome seem to reflect changes in digestive health, said Anna Garber, PhD, of the School of Veterinary Medicine at the University of Glasgow, in the U.K.

Genomic Sequencing of Feces After Altering Diet, Environment

In their study, Garber and her fellow researchers performed genomic sequencing on fecal samples from six healthy, adult Welsh Pony geldings undergoing two abrupt diet changes over 28 days.

The ponies first spent a month living full-time on grass pasture. The researchers then abruptly moved the ponies into individual box stalls for 14 days, where they received about 4-5 kilograms (9-11 pounds) of hay per day—rations designed to replicate real-life scenarios of riding horses. At the conclusion of that two-week period, the researchers instituted another abrupt change, moving the ponies back to group-living in a grass pasture.

The researchers found that the ponies’ microbiomes were relatively similar regardless of whether they were consuming grass pasture or a hay diet, she said. However, her team observed notable differences in the ponies’ microbiomes in the first three days after the abrupt change from hay to grass and vice-versa. Further, during those first three days the ratios of certain kinds of bacteria in the microbiome shifted, indicating the gut’s efforts to adapt to change. Likely, it was responding not only to the dietary change but also the environmental change, including differences in location and social situation, said Garber.

“It’s important to remember that change from grass to hay and from hay to grass is not only a change to the diet but also a change to the way the horses are managed, which includes temperature and humidity, light regime, exercise, social interaction, etc.,” she said.

Modified Ratios of Key Bacteria

Specifically, the researchers noted a flip in the Bacteroidetes-to-Firmicutes ratio right after changing regimes, Garber explained. When the diet was stable—whether grass or hay—Bacteroidetes dominated Firmicutes. But in the first few days of abrupt change, Firmicutes became the dominant bacteria. Both human and equine studies indicate that obesity is associated with a higher ratio of Firmicutes over Bacteroidetes. In horses, science has also shown that healthy horses have more Firmicutes, whereas those with colitis have more Bacteroidetes. So while the ratio’s effects aren’t clear, it’s worth noting that the balance shifts abruptly when the horse’s diet changes abruptly, indicating the gut is working to adjust to the change, Garber said.

“It is well-known that when microbiota in the gut is balanced (what is call symbiosis), horses can efficiently digest their feed, and the risk of the digestive upset is lower,” she explained. “Abrupt changes to the diet, on the other hand, may disrupt this balance and lead to dysbiosis.”

The scientists also observed an increase in the relative presence of Lactobacillus bacteria when going from hay to grass, Garber said. Because Lactobacillus bacteria produce lactic acid, an increased amount might cause a significant drop in hindgut pH in those first few days on pasture.

“Reductions of pH in the gut may lead to acidosis, diarrhea, and colic,” Garber said. “It’s also not beneficial for the fiber-degrading bacteria, which may die and release toxins and in turn potentially lead to laminitis.”

The team also found significant changes in other major kinds of bacteria following abrupt dietary changes. “This would mean that effect that abrupt dietary changes have on the gut microbiota of the horse is broad and not limited to a single bacterial species,” she said.

The exact effects of these changes aren’t clear, but evidence suggests they could be associated with metabolic upset in some horses, leading to colic and/or laminitis.

“Horses often experience sudden changes from hay to grass when we turn them out in spring when the grass starts to grow better and from hay to grass when we bring them back in to their stables in autumn when grass on pastures becomes scarce,” said Garber. “So these changes are common to many horses and are likely to cause digestive upsets and increase the risk for health problems like acidosis, colic, and laminitis.”

Diet Changes Affect All Horses

The research team recognized distinct individual differences from pony to pony, said Garber. Although none of the study ponies experienced clinical signs of health problems, they all had varying degrees of microbiome changes.

While this might explain why some horses have obvious reactions—such as colic—to abrupt dietary changes, it also suggests these changes affect most horses whether we realize it or not.

“Even when horses do not show clinical signs of microbial upset, the changes may still happen subclinically without us noticing it,” Garber said. “Long-term, these changes may also lead to negative health effects.”

Future research will focus on evaluating nutritional tools, such as probiotics, to “eliminate digestive upsets caused by abrupt dietary changes,” said Garber.

About The Author

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Passionate about horses and science from the time she was riding her first Shetland Pony in Texas, Christa Lesté-Lasserre writes about scientific research that contributes to a better understanding of all equids. After undergrad studies in science, journalism, and literature, she received a master’s degree in creative writing. Now based in France, she aims to present the most fascinating aspect of equine science: the story it creates. Follow Lesté-Lasserre on Twitter @christalestelas.

Getting to the Point: Equine Acupuncture

Read about the existing science behind acupuncture and what you should know before scheduling an appointment for your horse.

 

Getting to the Point: Equine Acupuncture

A review of the existing science behind equine acupuncture

With tightening sport horse competition drug regulations, increased scrutiny surrounding horse racing, and the general public’s desire to turn toward natural alternatives to medications, many veterinarians are seeing a rising demand for equine acupuncture. In the Western Hemisphere acupuncture has become an increasingly acceptable treatment modality. In fact, a 2017 survey of 423 horse owners in the U.K. found that 81% were willing to try a complementary or alternative form of veterinary medicine.1

Even if you are open to equine acupuncture, how much do you really know about this therapy? In this article we’ll explore the scientific basis of equine acupuncture, so you can come to your own informed decision about pursuing it to treat your horse’s ailments.

A Primer on Terminology

Many people use words such as holistic, alternative, complementary, and integrative medicine interchangeably. Although each of these categories includes acupuncture, each term has a distinctly different meaning.

Holistic medicine refers to a type of practice that looks at an animal as a whole while considering its environment and nutrition. Alternative medicine uses nonmainstream practice to replace conventional medicine, while complementary medicine uses conventional medicine together with nonmainstream practice. Integrative medicine combines all forms of holistic care, wellness, and medical practice in a coordinated fashion.

The History Behind Equine Acupuncture

Acupuncture is simply the stimulation of a specific point using a sharp object, such as a needle, to create therapeutic effects. Equine veterinary acupuncture traces back to ancient China’s Tang Dynasty in 618-907.² Although its origins have not been described, many feel it might have been observational, from recording unintentional treatments from being struck with sharp objects, thus serving as the longest clinical trial in medical ­history.

Despite its popularity, equine acupuncture has limited scientific evidence behind it. Researchers have conducted only two systematic reviews of companion animal acupuncture literature in the English language, and both concluded that most scientific evidence of veterinary acupuncture’s efficacy was nonexperimental and of low quality (not randomized and controlled trials) and, therefore, inconclusive.

How Does it Work?

Western-medicine-trained horse owners and veterinarians can struggle to understand acupuncture in traditional Chinese veterinary medicine (TCVM) terms—words like qi, theory of five elements, internal and external pathogens, meridians, and yin and yang.

From a Western perspective, acupuncture works through neuromodulation, meaning it normalizes function throughout the nervous system. Acupuncture points correspond to areas of decreased electrical resistance and increased conductivity, as well as increased density of free nerve endings, small blood and lymphatic vessels, and mast cells (immune cells found in connective tissues).

From a physiology standpoint, acupuncture elicits a response at different levels of the nervous system.³ First, it causes local effects, such as increasing blood flow to a certain point and relaxing the surrounding muscle and tissue. Second, it causes segmental effects, as most meridians (pathways of acupuncture points) correlate with nerve pathways. This means stimulating an acupuncture point can cause nerve impulses to travel up the pathway and into the spinal cord. Third, it has central effects, meaning functional MRI (brain imaging) has shown different effects on the brain when an acupuncture point is stimulated. Finally, it affects the endocrine (hormone) system by changing the level of natural chemicals and opioids in the central nervous system.

Is it Effective?

As early as 1997, the National Institutes of Health concluded that acupuncture was effective in treating human nausea and dental pain and was useful for myriad medical issues ranging from osteoarthritis to low back pain to asthma.4 Since then, researchers have performed many case studies and experimental studies on the efficacy of acupuncture in horses, dogs, and cats. However, in a review of 843 references, Canadian scientists found only four hypothesis-driven (more likely to be scientifically sound) studies.5

Meagan Smith, DVM, Dipl. ABVP, assistant professor of Clinical Equine Field Service at the University of Pennsylvania’s New Bolton Center, in Kennett Square, primarily uses acupuncture “for musculoskeletal maintenance or to help musculoskeletal issues,” she says. “Trainers and riders of the horses I perform monthly maintenance treatments on truly believe their horses feel better for at least a couple weeks after treatment—more supple and freely moving.”

 

Indeed, the most common indication for acupuncture in companion animal literature is to alleviate pain and treat lameness conditions. Researchers have found acupuncture to be 98% effective for treating back soreness in companion animals (dogs, cats, and horses), with increased pain threshold (measured as twitching in response to heat stimulus), increased skin temperature, and increased endorphins in the spinal fluid.5

Penelope Rochelle, DVM, CVA, CVSMT, equine acupuncturist and co-owner of Blue Sage Veterinary Wellness Center, in Little Silver, New Jersey, finds acupuncture “to be very effective … for the treatment of sports injuries in equine athletes, navicular/heel pain cases, and equine neck and back dysfunction. It is also instrumental in helping reinforce postural changes necessary for a healthier spine and greater athleticism.”

When used to treat arthritis, acupuncture seems to provide pain relief, although it does not reverse the process. Studies on its efficacy with lameness cases have produced mixed results. For example, in a single clinical study involving horses with laminitis and navicular disease, researchers found no significant difference in lameness between those treated with acupuncture and those not.

For treatment of gastrointestinal (GI) disorders, acupuncture’s efficacy comes from its ability to alter blood flow to organs, decrease pain by releasing opioids into the bloodstream, and normalize GI motility.6 Acupuncture should not, however, replace colic surgery. Although it increased affected horses’ pain thresholds in one study, it was not as effective as readily available injectable medications such as butorphanol.² Acupuncture also does not decrease clinical signs of colic pain and is not recommended as the primary intervention for colic. For horses with diarrhea, acupuncture points do seem to have some positive effects on regulating GI motility.6

For respiratory conditions such as equine asthma, study results show that acupuncture can help dilate the airways, making it easier for affected horses to breathe. That said, clinical trials have not shown statistically significant differences between lung parameters of equine asthma patients treated with or without acupuncture.

Infertility is a common area of application for acupuncture, especially in human medicine. In horses acupuncture reduces abnormal fluid accumulation in the uterus, resulting in increased fertility.² Aquapuncture (injection of solution into acupuncture points) can also help regulate the heat cycle and, so, reduce the need for high-dose medications. An integrative approach including TCVM and Western medicine can, therefore, effectively normalize equine patients with reproductive diseases.

Physicians use acupuncture to treat various ophthalmic conditions in humans, including dry eye and glaucoma. Although stimulating local acupuncture points around the eye seems to be anecdotally effective, and efficacy has been proven in dogs and rabbits, there have been no controlled studies performed specifically in horses to support this.

Nicole Estes, DVM, associate practitioner at Genesee Valley Equine Clinic, in Scottsville, New York, and owner of Woods Dry Veterinary Services, has used acupuncture “to help control pain and other clinical signs associated with glaucoma and equine recurrent uveitis (aka moon blindness). I am always quick to remind owners that we are treating a disease process with a balanced approach, utilizing Western medications along with Eastern medicine,” she says.

Neurologic conditions in horses resulting from peripheral nerve injuries seem to respond well to acupuncture. For example, sweeney (suprascapular nerve paralysis in the shoulder area), facial nerve paralysis, and laryngeal neuropathy (roaring) appear to respond to electroacupuncture treatment (electrical stimulation of acupuncture points).6

Researchers have shown that four horses suffering from anhidrosis (an inability to sweat) that received aquapuncture in conjunction with other TCVM treatments experienced positive results.²

What You Should Know Before Scheduling an Appointment

Most acupuncture sessions last about 30 minutes. Based on his or her clinical experience, your veterinarian will need to perform at least three treatments to see improvement in lameness conditions. While acupuncture is a safe modality with few to no harmful effects reported, talk to your veterinarian before having acupuncture performed on horses that are pregnant, very young, very old, or have been diagnosed with critical illnesses.

“One of the biggest attributes of acupuncture is that it very rarely has negative side effects, especially when compared to conventional treatments for chronic disease states,” says Rochelle. “It is often successful in cases where no other options are available or where all other treatments have tried and failed. It also provides an alternative in cases which cannot be treated with more aggressive means.”

It is important to seek a qualified acupuncture practitioner, as many acupuncture points are located near joints and other important anatomical structures. Acupuncture practitioners must be licensed veterinarians. Although there is no comprehensive directory of equine acupuncturists, many schools list practitioners who have completed training and been certified by those programs:

Take-Home Message

Research results on acupuncture’s effects on various equine conditions are mixed. The studies that do exist support using acupuncture to treat back pain, relieve arthritis pain, improve pain threshold in colic, regulate GI motility in chronic diarrhea cases, and help treat fertility, nerve paralysis, and anhidrosis. Limited evidence exists as to its efficacy for treating equine asthma, and no equine-specific studies have been conducted on its effects on eye conditions. In general, we need more well-designed experiments to generate more scientific evidence on acupuncture’s efficacy and place in treating equine conditions and to discover what points and acupuncture methods are most effective.


References

1. Thirkell J, Hyland R (2017). A survey examining attitudes towards equine complementary therapies for the treatment of musculoskeletal injuries. Journal of Equine Veterinary Science. 59 (2017) 82–87.

2. Tangjitjaroen W, Shmalberg J, Colahan PT, Xie H (2009). Equine acupuncture research: An update. Journal of Equine Veterinary Science. 29(9), p. 698-707.

3. Robinson, N. (2009). Making sense of the metaphor: How acupuncture works neurophysiologically. Journal of Equine Veterinary Science. 29(8): p. 642-644.

4. National Institutes of Health. (1997, Nov. 3-5). Acupuncture.

5. Rose WJ, Sargeant JM, Hanna WJB, Kelton D, Wolfe DM, Wisener LV (2017, Dec. 11). A scoping review of the evidence for efficacy of acupuncture in companion animals. Animal Health Research Reviews. 18(20): p. 144-185.

6. Shmalberg J, Xie H (2009). The clinical application of equine acupuncture. Clinical Techniques. 29(10): p. 753-760.

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Jean-Yin Tan, DVM, Dipl. ACVIM-LAIM, is an equine internal medicine specialist and faculty member at the University of Calgary Faculty of Veterinary Medicine. She trained previously in New Jersey, Minnesota, and California and subsequently spent six years in private practice, including owning an equine specialty practice in New York State. Her interests include equine infectious disease and respiratory disease.

Not All Equine Heart Murmurs Are Created Equal

A heart murmur diagnosis can raise many questions: Is my horse safe to ride? Is my horse going to die? Is there anything I can do? The answers to those questions usually require further investigation.

Not All Equine Heart Murmurs Are Created Equal

No one wants to hear their horse has a heart murmur. The diagnosis can raise many questions: Is my horse safe to ride? Is my horse going to die? Is there anything I can do? The answers to those questions usually require a deeper dive into the diagnosis to determine the specific type of heart murmur the horse has and how significant it might be.

Amy Polkes, DVM, Dipl. ACVIM, provides cardiac evaluations through her mobile practice, HV Equine Internal Medicine, which serves Maryland and the surrounding states. She discussed heart murmurs during a recent presentation at the 2020 Northeastern Association of Equine Practitioners Symposium.

Most people are familiar with the two-beat “lub-dub” sound a normally functioning heart makes. The beats correspond to valves closing as blood flows through the heart. The first heart sound (lub) happens when the mitral and tricuspid valves close and is referred to as S1. The second heart sound (dub) takes place when the aortic and pulmonic valves close and is referred to as S2.

 

The time between S1 and S2, when blood is being ejected from the ventricles, is called systole. The time between S2 and the next S1, when the ventricles are filling, is known as diastole.

A murmur can be defined as an atypical sound of the heart, such as whooshing or swishing. A systolic murmur is heard between S1 and S2, while a diastolic murmur will be heard after S2 and before the next S1. It is also possible for a murmur to be both systolic and diastolic, in which case is it called a continuous murmur.

“When we’re characterizing a murmur, the most important thing is the timing and recognizing whether it is systolic or diastolic,” Polkes said, “because that is very important in what you’re going to be thinking the cause of the murmur is.”

Determining the Type of Murmur

In addition to identifying whether the murmur is systolic or diastolic, a veterinarian will determine whether the murmur is functional or pathologic.

“The type, functional versus pathologic, will help us decide whether the murmur is really that significant,” Polkes said. “A functional murmur is a manifestation of normal blood flow—there’s not actually a problem at the valve—versus pathologic, where there is abnormal blood flow and a problem at one of the valves.”

Functional murmurs can be broken down into functional systolic murmurs and functional diastolic murmurs, which veterinarians can differentiate by their sounds and locations. While functional diastolic murmurs are uncommon, functional systolic murmurs can be caused by changes in blood flow that may occur due to things such as colic, fever, exercise, pain or anemia. When the blood flow returns to normal—the horse is no longer colicky, for example—the murmur goes away.

Pathologic murmurs can also be systolic or diastolic, and they can be further differentiated into genetic or acquired murmurs. Again, the location of the murmur will help your veterinarian determine its type. Certain murmurs can more readily be heard on the horse’s right side rather than the left, for example, or at the apex of the heart as opposed to the base.

Murmurs are also graded based on the severity. The grading scale of 1 to 6 allows your veterinarian to set a baseline and track the progression of you horse’s murmur over time.

“A grade 1 is really difficult to hear and probably clinically insignificant,” Polkes said. “A grade 2 is readily heard. It’s soft sounding, but you can consistently hear it. A grade 3 can definitely be heard and may radiate into the chest. Then grade 4 to 6 get louder and louder. The biggest difference is at a grade 5 and 6, you’re going to actually feel a thrill on the chest.”

The Importance of Diagnostics

Depending on the type, characterization of and grade of the murmur, diagnostics should be considered, even if the horse doesn’t have clinical signs. Those diagnostics would include ultrasound of the heart, also known as an echocardiogram, and electrocardiogram to examine the structure, size and function of the heart. This is important to determine the level of concern and if further diagnostics or treatment is warranted.

“Diagnostic testing is essential when the horse is being ridden,” Polkes said. “If your horse was lame, you would have a lameness exam. If your horse has a murmur, you should really have a cardiac evaluation. It’s very important.”

Polkes also recommends yearly cardiac exams, where a veterinarian listens to your horse’s heart on both sides of the body to make sure there aren’t any new murmurs or changes. Regular examinations and record keeping can help you take the best care of your horse’s cardiac health.

About The Author

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Stacy Pigott is a freelance writer based in Tucson, Arizona. For 25 years, Stacy served as editor for various equine publications in the Quarter Horse racing and Western performance horse industries. She currently works at the University of Arizona, where she is a public information officer covering health sciences news and research. She hopes to compete in eventing and jumping with her OTTB Nicky.

Locomotion of Circling Horses

Horses experience changes in force on their bodies and limbs when they turn. This can affect lameness exams, making them look both more and less lame. And should racetracks be banked?

Locomotion of Circling Horses
Horses lean toward the inside as they take turns, fighting against a pull that would otherwise make them “topple over to the outside.” They dig their hooves into the ground and push down and out, as the ground pushes back against their hooves. The resulting biomechanical shifts alter the horse’s symmetry, balance, and even dynamic height, which can affect musculoskeletal health from head to toe, performance, and even lameness assessments, said one equine biomechanics specialist. 

“Negotiating a circle involves a change of direction, and a change in direction causes inward acceleration toward the center, which is called centripetal acceleration,” said Sarah Jane Hobbs, PhD, of the University of Central Lancashire Centre for Applied Sport and Exercise Sciences, in the U.K.

Hobbs gave a one-hour presentation on locomotion in circles during the Centaur Biomechanics Virtual Equine Sports Science Summit on Oct. 3.

The mechanical equation for centripetal acceleration takes both radius and velocity into consideration, but by different amounts, Hobbs explained. “So the speed of the turn will be more influential than how sharp the turn is,” she said.

Applied to the horse, this means the faster he goes around a curve, the greater centripetal force he must create to make the turn. He does this through “pushing outward” with his body, she said. “The outward push can be achieved by changing limb position, body position, or muscular effort, and the effect of these changes can have an influence on the horse’s balance,” said Hobbs.

Horses also tend to lean inward—some more than others, depending on their muscular development and discipline, with dressage horses leaning less than racehorses, for example. The lean makes the horse “shorter,” in that his vertical height from ground to withers is reduced, which is important for clinicians to keep in mind as a possible compounding effect on lameness exams.

How Circling Affects Lameness and Lameness Exams

How a horse copes with a turn can affect his gait, making him appear more or less sound than he would be on a straight line. “Circles can exacerbate lameness on the outside forelimb, probably due to increased vertical ground reaction force (the way the ground pushes back against the horse’s feet), or on the inside hind limb, possibly due to altered pelvic and limb posture,” said Hobbs.

Meanwhile, subtle outside hind-limb lameness might appear improved on a curve. “It could actually be masked on a circle due to the hind-limb asymmetry that you would find normally during turning,” she explained.

Horses might also look lame on turns even if they’re not, she added. “Circles can give the impression of inside forelimb or inside hind-limb lameness, with a head nod on the outside forelimb or hip hike on inside hind limb,” said Hobbs.

High-Speed Turns: Should Tracks Be ‘Banked’?

At high speeds, the centripetal force needed to make a tighter turn can be so great that the horse slows down—an important consideration for racetrack, training track, and cross-country course designs, said Hobbs. When the ground is soft, horses can dig their hooves in better for these curves—but with the countereffect of having a longer stance time (when the foot is on the ground). When the ground is hard, horses must compensate for the centripetal force in other ways to keep from falling, either by slowing down or changing their positions in ways that could, in certain circumstances, lead to musculoskeletal injury or excess wear and tear.

“Banking” tracks might be a solution to help horses negotiate high-speed turns, said Hobbs. Banked tracks are common in sports such as car and motorcycle racing, with raised surfaces at curves to keep pilots from skidding off the track.

“The mechanics of turning are less demanding when negotiating banked turns, which is a consideration for food for thought for track designers,” she said.

A likely biomechanical consequence of banked tracks, however, would be increased speed. In high-speed turns with no banking, “horses have to slow down because they are limited by the amount of force they can produce to make the turn,” said Hobbs. “If you did start to bank those tracks, you’d probably see differences in speed.”

The logistics of maintaining a banked track, however, could make it very difficult to actually have horses racing on them, she added.

About The Author

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Passionate about horses and science from the time she was riding her first Shetland Pony in Texas, Christa Lesté-Lasserre writes about scientific research that contributes to a better understanding of all equids. After undergrad studies in science, journalism, and literature, she received a master’s degree in creative writing. Now based in France, she aims to present the most fascinating aspect of equine science: the story it creates. Follow Lesté-Lasserre on Twitter @christalestelas.

Major U.S. Horse Racing Organizations Jointly Fund First-Of-Its-Kind Study On The Effects Of Furosemide In Two-Year-Old Racehorses

MAJOR U.S. HORSE RACING ORGANIZATIONS JOINTLY FUND FIRST-OF-ITS-KIND STUDY ON THE EFFECTS OF FUROSEMIDE IN TWO-YEAR-OLD RACEHORSES

Study to be Led by Washington State University’s Department of Veterinary Clinical Services

 Laurel, MD (October 29, 2020) – The Stronach Group together with Breeders’ Cup Ltd., Churchill Downs Inc., Keeneland, the Kentucky Horse Racing Commission, the Kentucky Thoroughbred Association and the New York Racing Association, Inc. have agreed to jointly fund North America’s largest study on the effects of furosemide and on the prevalence and severity of Exercise-Induced Pulmonary Hemorrhage (EIPH) in two-year-old racehorses.

The study, formally titled Furosemide: Its Effects on the Prevalence and Severity of Exercise-Induced Pulmonary Hemorrhage (EIPH) and the Immune System’s Normal Response to Exercise in Two-Year-Old Racehorses, began this month and is being led by Dr. Warwick Bayly and Dr. Macarena Sanz from the Department of Veterinary Clinical Services at Washington State University’s College of Veterinary Medicine. This study represents the largest study ever to focus on evaluating the effects of furosemide on two-year-old racehorses.

The study will be focused on two-year-old racehorses only and will aim to address the debate surrounding whether or not injection of furosemide has beneficial, detrimental or no effects on the welfare of these racehorses. The use of furosemide and its effects has been a dominant issue confronting North American racing for more than a decade. The study offers an opportunity to address unanswered questions at the heart of furosemide use, namely:

  1. Does the administration of furosemide four hours before racing and/or training reduce the severity of EIPH in two-year-old racehorses?
  2. Does the pre-race administration of furosemide four hours before racing effect a horse’s performance?

The study will evaluate the endoscopic exams from at least 600 horses from three groups representing the major racing jurisdictions of California, Delaware, Florida, Kentucky, Louisiana, Maryland, Pennsylvania, New Jersey and New York. Horses will be evaluated in three groups: 1) those who are given furosemide at least 48 hours before racing or not at all; 2) those who are given furosemide 24 hours before racing or not at all and; 3) those who are administered furosemide four hours before racing. Veterinary practitioners from each of the jurisdictions will be asked to recruit trainers who are existing clients to voluntarily participate in the study.

“This study provides an opportunity to fill a critical knowledge gap on the use of furosemide,” said Dr. Warwick Bayly, Professor, Equine Medicine, Washington State University College of Veterinary Medicine. “As a first-of-its-kind study of this depth, it is our hope that once completed we will be able to provide additional information that will enable the horse racing industry to address the regulation of furosemide in the United States from a scientifically-informed perspective.”

“The current patchwork of rules and regulations across the United States regarding the administration of furosemide does a disservice to the horses and the practitioners who care for them,” said Dr. Dionne Benson, Chief Veterinary Officer, The Stronach Group. “This study is an opportunity for industry stakeholders to come together to invest in meaningful steps to address pressing questions so that we may develop a higher and more consistent standard of rules and regulations.”

“The use of Lasix has long been a highly debated topic. This is our opportunity, as advocates for the safety and welfare of our racehorses, to collect and analyze vital real-life information that can be used to help answer some questions regarding the use of Lasix and its effect, but also guide common-sense regulation around Lasix use,” said Dr. Will Farmer, Equine Medical Director, Churchill Downs Incorporated.

“This study represents a unique collaboration of North American racing interests to further understand the true rate of EIPH in young racehorses through endoscopic examinations performed in post-race settings,” said Dr. Stuart Brown, Equine Safety Director – Sales and Racing, Keeneland. “The potential to gain insight under the present landscape of furosemide use across various racing jurisdictions will help shape decisions that benefit the safety and welfare of the equine athlete in competition.”

Preliminary results from the study are expected to be available in Spring 2021, assuming the quantity and quality of the samples satisfy the requirements for statistical relevance as set out by Dr. Bayly and Dr. Sanz.

Blanketed Horses Eat Less Hay

Researchers found blanketed horses during a Wisconsin winter ate 8% less free-choice hay than their unblanketed peers while maintaining similar body conditions.

Study: Blanketed Horses Eat Less Hay

When it comes to the “hot” topic of blanketing, a metabolic balance is at play, according to results of a new study. Researchers led by Michelle DeBoer, PhD, an assistant professor at the University of Wisconsin in River Falls, found blanketed horses ate 8% less free-choice hay than their unblanketed peers while maintaining similar body conditions.

The Study: Free-Choice Hay and Blankets vs. No Blankets

DeBoer and her fellow researchers blanketed eight adult horses housed in a dry outdoor paddock in Wisconsin from December to January. Nearby in a second dry outdoor paddock, they left eight other adult horses, similar in breed, body weight, and body condition to the first eight, without blankets for the same time period. Each group of horses had access to identical bales of grass-legume hay, and they could eat as much as they wanted.

The researchers found that, on average, the horses’ weight and body condition remained similar between groups throughout the study. But when the scientists compared the weight of the hay bales in each group before and after the study, they noted the unblanketed animals had eaten more hay. Calculating a daily average per animal, they determined that the unblanketed horses consumed 2.51% of their body weight whereas the blanketed horses consumed 2.31% of their body weight—a drop of approximately 8% of total hay fed.

“For a 1,000-pound horse, this would equate to blanketed horses consuming approximately 2 pounds less hay on a daily basis,” DeBoer said. The horse’s consumption never dropped below the recommended minimum forage intake level of 1.5-2% of body weight for a healthy adult, she said.

Less Hay, but Not a Weight Loss Strategy

“Our study demonstrated that horses tended to voluntarily reduce their intake when blanketed,” said DeBoer. “While this adds up when feeding a herd of horses over an entire winter, it does not mean horses can be fed drastically less hay if they are blanketed.”

While blanketing horses could result in a more slowly depleting hay supply, it doesn’t mean owners should deprive their horses of hay because they’re blanketed, DeBoer added. Horses need hay to meet their nutritional needs and support their gastrointestinal (GI) health.

“A horse’s GI tract is designed to consume forage continuously throughout the day, and we do not want to disrupt that or we may put the horse at risk for GI problems such as ulcers,” DeBoer said. “As a result, if a horse owner is reducing hay fed based on the results of this study, it is important to still feed the horse adequate hay, which will vary based on the condition and type of horse (maintenance, exercising, pregnant, lactating).”

The reduced hay consumption shouldn’t be seen as a weight-loss method, she added. Just because the horse eats less hay doesn’t mean he’s losing weight. In fact, the opposite is true, she explained. The blankets can add so much body warmth that the horse ends up expending less energy to heat himself, and if he doesn’t reduce his consumption enough to meet that balance, he could gain weight.

“It is crucial that horse owners continuously monitor the horse for changes in body condition and weight,” she said. “Based on the condition, or changes in condition, of the horse, owners can make adjustments to the diet as needed with help from a veterinarian or nutritionist.” she said.

Regardless of whether the horse tends to lose or gain weight while blanketed, owners must check their horses’ body condition regularly to ensure hay intake is balanced with nutritional needs, said DeBoer. Because blankets can hide body condition, people should take blankets off at least several times a week, if not daily, for a reliable evaluation.

To Blanket or Not?

Owners should also consider that the labor and expense of blanketing versus not blanketing is a tradeoff, DeBoer said. “Blanketing can be a very time-consuming and labor-intensive process that should not be taken lightly.”

Editor’s note: See sidebar for DeBoer’s health-oriented blanket maintenance recommendations.

This study provides one more element to consider among many affecting the decision to blanket, DeBoer said. In particular it can help owners make choices when hay is scarce. “In recent years, we have had hay shortages that have driven up hay prices and led to horse owners having difficulty in finding horse-quality hay to provide to their equines,” she said. “While this research demonstrated minimal cost-savings in comparison to the cost of purchasing and maintaining a blanket, blanketing may provide an option for horse owners during times when hay availability or labor is limited.

“As a result, I think this is valuable information to help horse owners make more informed management decisions during these times and to understand how blanketing may influence horses and their feeding behaviors,” she said.

About The Author

mm

Passionate about horses and science from the time she was riding her first Shetland Pony in Texas, Christa Lesté-Lasserre writes about scientific research that contributes to a better understanding of all equids. After undergrad studies in science, journalism, and literature, she received a master’s degree in creative writing. Now based in France, she aims to present the most fascinating aspect of equine science: the story it creates. Follow Lesté-Lasserre on Twitter @christalestelas.