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2014 Tennessee Equine Hospital Lecture Series:
By Allison Armstrong Rehnborg
Photos by Ryan Rehnborg
On August 19, 2014 the Tennessee Equine Hospital devoted an evening of lectures to “solving the mystery of the skinny horse,” featuring presentations by Dr. Rena Chang, equine dentist; Dr. Christine Cocquyt, equine internist; and guest speaker Dr. Hoyt Cheramie, a Merial representative. Ranging from ulcers to dental work to internal medicine, the evening ran the gamut of potential causes for weight loss in horses and offered some interesting insights into how the horse’s digestive system functions.
The evening began with Dr. Cheramie’s presentation on equine gastric ulcer syndrome, a common condition that can seriously affect a horse’s health. Similar to gastroesophageal reflux disease in people, EGUS involves the imbalance of acid in the horse’s stomach. Unlike the human stomach, where the lining of the esophagus stops when it reaches the stomach, the lining of a horse’s esophagus extends well into the stomach, where it is vulnerable to the effects of stomach acid. Unlike humans, who only produce stomach acid at intervals, horses produce stomach acid 24/7. Left to natural behavior patterns, a horse will spend most of its time with its head down, grazing. By steadily ingesting forage and continually producing saliva, a horse is able to keep the acid in its stomach properly buffered, reducing the likelihood of ulcers. But if frequently stalled and fed only at intervals, like many show horses today, the acid content of the stomach can become unbalanced, resulting in the development of painful ulcers.
Signs of ulcers in horses include weight loss, reduced appetite, poor hair quality, recurrent colic, attitude changes, and poor performance. Dr. Cheramie explained that these signs are often so subtle that they either go unnoticed or are attributed to other conditions, and that there is no correlation between the severity of a horse’s ulcers and its symptoms. The best way to diagnose ulcers involves gastroscopy: by sliding a camera on a scope through the nasal passage and into the stomach, veterinarians are able to take photos of the stomach lining and identify ulcers.
Dr. Cheramie concluded his lecture by recommending Gastrogard and Ulcergard. Gastrogard contains omeprazole, which is an acid pump inhibitor that inhibits the final step in acid production for up to 24 hours. The only FDA-approved treatment for ulcers, Gastrogard is administered in paste form. Ulcergard, its sister product, contains a low dose of omeprazole which can be administered prior to stressful situations (such as showing or hauling). As an adjunctive therapy, Dr. Cheramie recommended feeding hay in closely-woven nets or webbing on the ground, in order to slow down the horse’s intake and increase saliva production. He also advised feeding a flake of alfalfa now and then, as the legume hay’s high calcium and phosphorus levels work well to buffer stomach acid, like Tums for horses.
Next, Dr. Rena Chang took the podium. A graduate of the University of Florida College of Veterinary Medicine, Dr. Chang joined the hospital as an associate in 2012. In her daily work, Dr. Chang focuses on equine wellness and dentistry – two topics that are closely related. While Dr. Chang acknowledged that floating (the filing down of points and hooks on equine teeth) is the most common aspect of equine dentistry, she also defined her field on a much broader scale for the audience.
“Equine dentistry is the prevention, diagnosis, and treatment of conditions in the horse’s mouth,” she explained, noting that her work includes floating, the treatment of retained caps, tooth extractions, and treating oral abscesses and infections.
Floating, or “occlusal equilibration” involves balancing the teeth to maximize the grinding of feed. Dr. Chang explained that horses have “hypsodont dentition,” or teeth that continually erupt from the gum line throughout their lives. In the perfect equine mouth, the horse’s daily chewing and grinding would naturally wear down its teeth at the same rate as eruption, ensuring a consistent grinding surface across all teeth. However, few equine mouths are perfect, which means that sites can develop in a horse’s mouth where the upper and lower teeth do not grind against one another, causing abnormalities such as “hooks,” “waves,” or “steps” to occur – all of which can interfere with the horse’s ability to eat and, subsequently, to gain or maintain weight. That’s where floating comes in.
Common symptoms of dental problems in horses include weight loss, bad breath, facial swelling, nasal discharge, the development of avoidance behaviors (such as holding the head to the side, tossing the head, or resisting basic commands from the bit), and “quidding.” If a horse is unable to chew properly, he may ball up forage and grass and hay in his mouth into a cigar-like shape and then spit it out in a “quid.”
As in many aspects of health care, Dr. Chang stressed that an ounce of prevention is often worth a pound of cure – and equine dentistry is no exception. Including a dental check is an important part of every horse’s annual wellness exam, and she detailed the procedures for a typical exam.
“When I approach your horse, I’m already starting my exam,” she explained. “I may be patting him, but I’m checking for swelling and seeing if his breath smells bad. If it does, I may focus more on one side of his mouth or the other.”
For a dental exam on a skinny horse, Dr. Chang explained that her primary goal would be to identify and resolve any discomfort in the mouth, and to maximize contact of occlusal grinding surfaces so as to increase the horse’s ability to properly chew its food. Sometimes, the problem of weight loss can be at least partially remedied by ensuring that a horse can chew – which, after all, is the first step in the digestion of nutrients.
Dr. Christine Cocquyt finished the lecture portion of the evening with a presentation on the “mystery of the skinny horse.” A graduate of the Kansas State University College of Veterinary Medicine, Dr. Cocquyt recently completed a residency in Internal Medicine at the University of Tennessee College of Veterinary Medicine.
During her talk, Dr. Cocquyt acknowledged that, when faced with a persistently skinny or underweight horse, many people yearn for a quick and easy fix, but that is rarely the case. Just as in equine lameness or colic, there are a multitude of reasons why a horse may lose weight.
First, Dr. Cocquyt advised the audience to assess their horses regularly, using the Henneke body condition scale. Ranging from 1 (poor) to 9 (extremely fat), a horse’s ideal condition often settles between 4 (moderately thin) to 6 (moderately fleshy). She noted that conformational issues can often confuse assessment, and recommended that horse owners assess their horses’ conditions “hands-on.” There is no substitute for placing your hands on your horse’s body to feel the thickness of fat or muscle coverings. The consistent use of a weight tape also works well for tracking a horse’s weight, if a scale isn’t readily available.
Next, Dr. Cocquyt moved into her approach to solving weight issues, noting that oral exams, blood work, fecal egg counts, ultrasounds, and gastroscopies are all useful diagnostic tools for a veterinarian and a horse owner to employ. She also recommended that horse owners take a good look at their feeding practices, especially when it comes to measuring feed.
“If I tell you to weigh your feed from now on with a kitchen scale, just play along,” Dr. Cocquyt said, explaining that feeding by weight is the most accurate way to ensure your horse is receiving the necessary calories.
The basics of good nutrition include providing constant access to fresh water and salt, and feeding a good-quality forage. Horses consume from 1.5% to 3% of their body weight each day, and over half of it should come from forage. Dr. Cocquyt also recommended fat supplements, such as ground flaxseed or oil, rice bran, or canola oil, and also listed a few of her favorite digestive aids for horses, such as ProBios, EquiPase, and GI Conditioner.
Recalling a recent patient who was a victim of “social starvation,” the veterinarian advocated feeding concentrates to horses separately, and not in groups. During group feedings of concentrates, one horse may be continually pushed aside and not get enough, resulting in weight loss, while other horses may eat more than their share, resulting in obesity. Keeping an eye on the conditions of your round bales and your pastures is also necessary, as round bales can quickly mold, and pastures can become overgrazed and choked with weeds while still appearing “green.”
As she finished her presentation, Dr. Cocquyt listed other common causes of weight loss in horses, include Cushing’s disease, inflammatory bowel disease, kidney, heart, and liver problems, and a host of other conditions, such as chronic infections, neoplasia, and heaves. Dr. Cocquyt stressed the importance of assessing your horse’s internal parasite load regularly by performing fecal egg counts; worms such as small strongyles can have a serious impact on weight loss or maintenance. Targeted deworming programs are an essential part of a horse’s overall health program.
As any horse owner who has ever struggled to feed a “hard keeper” knows, solving the mystery of the persistently underweight horse can be a long, challenging mission, riddled with frustration, expense, and a great deal of trial-and-error. Success in these “grocery games” often requires the help of an experienced veterinarian, who is perfectly equipped to evaluate your skinny horse from teeth to tail.
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