The Kentucky Equine Research Conference took place October 29-30 in Lexington, Kentucky. At this year’s conference, the company celebrated its 30th anniversary with a look back at how far equine nutrition and veterinary science have come.
Presenters from around the world reviewed advances made by researchers over the past three decades in the fields of equine nutrition, digestive health, musculoskeletal conditions, neurologic disease, and more. They shared how these gains in knowledge have come to improve horse health and welfare, and they provided some insights about future equine research directions.
Advances in nutrition were covered by Joe Pagan, Ph.D.; Laurie Lawrence, Ph.D.; Pat Harris, Ph.D., Vet.M.B.; Stephanie Valberg, D.V.M., Ph.D.; and Kristine Urschel, Ph.D.
Pagan founded Kentucky Equine Research in 1988 and, in the three decades following, he and his staff have witnessed the evolution of equine nutrition and research trends. He concentrated on five primary themes in his presentation: developmental disorders, skeletal health, gastrointestinal health, nutrient requirements, and unintended consequences of research. A surge of research on developmental orthopedic disease (DOD) took place in the 1980s, especially in relation to mineral deficiency. While correcting mineral imbalances helped many young horses, DOD continued to cause strife among breeders, especially in precocious, fast-growing horses. A large-scale study conducted by Kentucky Equine Research revealed that a relationship existed between glycemic response, the effect of carbohydrates on blood sugar, and osteochondritis dissecans (OCD), a form of DOD in which cartilage fails to properly turn to bone. Following this discovery, even more young horses were helped when farms implemented feeding strategies that limited starch in susceptible horses. Since the late 1990s, though, there has been little time spent on DOD within the research community.
Pagan commented on the ever-expanding base of knowledge concerning bone demineralization, which often occurs when horses are confined for long periods. A recent skeletal-health study by Kentucky Equine Research revealed the effect of a natural calcium source on bone mineral in racehorses in training. The researchers found that this particular calcium, which is found in the commercial product TriactonÂ®, increased bone density fourfold, which could have profound benefits to horses in training as well as those actively racing and showing. In terms of gastrointestinal health, Pagan talked not only about the gastric ulceration as a source of discomfort in horses, but also the rise of hindgut acidosis, which is an increased acidity of the cecum and colon that alters the natural population of microbes. He and his research team found that hindgut acidosis could be attenuated through the use of a novel feed supplement, encapsulated sodium bicarbonate, which is marketed as EquiShureÂ®.
In terms of nutrient requirements, Pagan mentioned the work done on nutrient digestibility and bioavailability over the last 30 years with specific emphasis on vitamin E, as research conducted in his laboratory has found that water-soluble natural vitamin E, such as that found in the product Nano-EÂ®, is much more bioavailable than synthetic sources of the vitamin. More recently, he discussed the potential for coenzyme Q10 to be used in feeding programs as a robust antioxidant.
As far as unintended consequences, Pagan described these as unexpected results from research. For instance, furosemide, or LasixÂ® , is a common medication given to racehorses and some other performance horses to prevent exercise-induced pulmonary hemorrhage, or bleeding. One side effect of furosemide is frequent urination, which causes horses to lose considerable electrolytes, wrecking their mineral balance. As a result of this knowledge, he developed an electrolyte specifically for horses given furosemide, called Race Recoveryâ„¢.
Laurie Lawrence, a professor at the University of Kentucky and a preeminent equine nutritionist, has explored various research interests during her career, and this diversity lent itself well to her work as chair of the National Research Council Subcommittee on Horse Nutrition, during which she oversaw the revision of Nutrient Requirements of Horses in 2007. At this year’s conference, she spoke on some pivotal moments in mineral research over the last 30 years, the primary of which occurred on foals and mares in regard to copper and zinc. She expounded on some recent work on phosphorus, which indicated requirements for that mineral could be fine-tuned.
Pat Harris, a veterinarian and nutritionist, heads up the equine research program at Waltham, and gave a retrospective on equine metabolic syndrome (EMS) through the decades. According to her, while the link between obesity and laminitis has been recognized for many centuries, it wasn’t until the 1980s when a potential association to insulin was proffered. Some obese ponies were less insulin sensitive than others, providing a possible connection between insulin resistance and laminitis. By 2010, veterinarians agreed to adopt the term “equine metabolic syndrome” to describe the phenotype of an animal with obesity and insulin resistance with a predisposition to laminitis. A subtle shift occurred to the definition of EMS in 2016, whereby it is now described as “a clinical syndrome associated with an increased risk of laminitis that includes insulin dysregulation and any combination of increased or regional adiposity, weight loss resistance, dyslipidemia, and altered adipokine concentrations.” Obesity is recognized as a globally important welfare issue for horses, Harris said. In one study conducted in North Carolina, U.S.A., 48% of horses were found to be overweight or obese. Owner education about optimal body weight is necessary to effect change.
Stephanie Valberg, D.V.M., Ph.D., a professor at Michigan State University and director of the university’s Neuromuscular Diagnostic Laboratory, provided information about the value of vitamin E as adjunct therapy for several neurological diseases, including equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM), equine motor neuron disease (EMND), and vitamin E deficient myopathy. The goal of supplementation in horses susceptible to these diseases, according to Valberg, is to increase the concentration of vitamin E in the central nervous system and muscle tissue.
Kristine Urschel, Ph.D, an associate professor at the University of Kentucky, discussed the direction of protein research in horses, where her two keys areas of focus have been understanding factors that regulate muscle mass in horses across the lifespan and assessing dietary protein and amino acid adequacy from immaturity to maturity. As far as the future, Urschel described a study she is currently undertaking in collaboration with Kentucky Equine Research. The study involves protein metabolism in the exercising horse, with the goal of looking at how feeding in proximity to exercise can influence whole-body protein metabolism.
The veterinary topics of the conference were covered by a clutch of five veterinary experts, all of whom had the distinguished honor of giving the Milne Lecture at the annual meeting of the American Association of Equine Practitioners: C. Wayne McIlwraith, B.V.Sc.; Steve Reed, D.V.M.; Nat White, D.V.M.; Al Merritt, D.V.M.; and Valberg.
C. Wayne McIlwraith, a pioneer in the field of equine orthopedics, spoke about his evolution as a veterinary surgeon and about the work he and his colleagues have done at Colorado State University. When asked what he believed to be his greatest accomplishments, McIlwraith cited recognizing the critical nature of synovitis and perfecting his work in arthroscopic surgery, as well as his ability to teach others how to perform the procedures. In addition, he spoke of developing the Orthopaedic Research Center, the largest orthopedic research program in the world. On the horizon at Colorado State is the Translational Medicine Institute, a continuation of the Orthopaedic Research Center. Transitional medicine is the use of basic laboratory research, preclinical research in vivo, and clinical examination that leads to patient success, with that we learn in animals often translating into improved medical treatments in humans. The outcome, according to McIlwraith, is better diagnosis and better treatment of the patient.
Steve Reed, professor emeritus from The Ohio State University and currently a veterinarian at Rood and Riddle Equine Hospital, spoke about advances in neurology. Back 30 years, Reed said that some individuals insisted that neurology was simply a euphemism for necropsy, but now there’s far more hope for horses with neurological problems. A particularly important finding occurred when veterinarians began to better understand wobbler syndrome, also called cervical vertebral stenotic myelopathy, including believing that the neck might be one of the most sensitive areas for developmental orthopedic disease. In addition to wobbler syndrome, another disease that propelled neurology to the forefront among horse owners was equine protozoal myeloencephalitis, or EPM, primarily because after some thorough research by scientists, it was found to be a treatable disease, for the most part. Two important things to watch for in the future, in regard to neurology, according to Reed, include (1) genetic testing to determine the etiology of neurological diseases through the use of next generation sequencing platforms, and (2) portable CT units, which will be invaluable for use on extremities, possibly becoming a game-changer for high-performance horses.
Focusing on colic, Nat White, a professor emeritus of equine surgery at Virginia-Maryland College of Veterinary Medicine’s Marion duPont Scott Equine Medical Center, gave a history on diagnostic techniques and treatments over the last 30 years. White believes that three areas deserve more research. First are more prospective epidemiologic studies are needed to understand the relationship of the environment and diet to mild colic, which represents more than 85 percent of colic in horses. Second is nutrition and understanding the microbiome in gastrointestinal health and function. New technology is allowing rapid identification of the flora in the horse’s intestinal tract in varied conditions. Third is use of stem cell research to define the response of the intestinal cells to insults and potentially to stimulate regeneration in injured intestine.
Further, White said the technology for genetic testing will also help to decide if there is a genetic predisposition to intestinal dysfunction. When combined with analysis of the microbiome, there may finally be answers for some of the questions about the cause of the most common type of colic: the simple colic with no specific diagnosis.
A forerunner in equine gastrointestinal health, Al Merritt, a faculty member at University of Florida for 25 years, is well known throughout the veterinary research community for his contributions in the understanding of gastric ulcers. Once equine gastric ulcer syndrome (EGUS) was recognized, Merritt said it was only natural to turn to therapeutic protocols, most notably agents that either buffered or blocked secretion of gastric acid. Effective antacid therapy promoted healing of squamous tissue, and this was somewhat good fortune given what researchers now know about the major role of gastric acid in the pathogenesis of squamous ulceration. Histamine-2 receptor antagonists were the antisecretory drug class of choice in human medicine in the 1980s and those that were available were, of course, formulated for human use and dosage. Were they effective in the horse, and at what dose? Ranitidine showed a reasonable effectiveness but, again, required administration three times a day.
Other agents tried early on included the PGE2-inducing compound sucralfate and other substances that presumably provided a protective coating of the squamous mucosa against acid damage, but these never took hold with horse owners in a big way. The same for oral-buffering agents, which were shown to have only a short-term effect.
Then came omeprazole, with the first studies of acid inhibitory effect in horses reported in 1992. Merritt subsequently worked with Merial, using a herd of cannulated horses at the Island Whirl Equine Colic Research Laboratory at the University of Florida, in the development of an oral paste formulation of omeprazole that was finally marketed as GastroGardÂ®. Then, another researcher led the critical trial of GastroGardÂ® that verified its beneficial effects for horses in training, which was reported in 1999. While this product was considerably more expensive than ranitidine, who could argue against a paste formulation that only needed to be given once a day? The rest is history, said Merritt.
In addition to her presentation about vitamin E, Stephanie Valberg also gave an overview of muscle disease in horses. In describing the changes in diagnosing muscle disease, she said a window into the world of equine muscle opened when researchers, in the 1970s, adapted the percutaneous needle biopsy technique for use in horses, making it possible to repeatedly sample unsedated horses and characterize the properties of equine muscle.
Also, neuromuscular diagnostic laboratories, such as those Valberg established at the University of Minnesota and now at Michigan State University, have formed the cornerstone for the identification of specific etiologies for exertional rhabdomyolysis in horses. A centralized site to receive muscle biopsies from across North America facilitates: (1) assimilation of the astute observations of large numbers of practitioners submitting biopsies; (2) accumulation of Â hundreds of cases from which to identify patterns of disease; (3) banking of biochemical and DNA samples that could be used to investigate the pathophysiology of disease subsets; and (4) formation of a research hub where breeders, equine practitioners, physiologists, biochemists, and molecular biologists could collaborate on muscle diseases in horses.
Finally, the remarkable development of genomic maps and the sequencing of the equine genome have provided new tools to investigate potential heritable bases for exertional rhabdomyolysis in horses.
Further coverage of the conference, as well as the text of the proceedings book, is available at ker.com.