The Horse

SEP 2017

The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.

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24 TheHorse.com THE HORSE September 2017 What Are the Risks? There are plenty of reasons to be concerned about your horse putting on weight, especially when he's recovering from an injury or dealing with a chronic lameness. "Additional weight means more stress on injured areas, even if the horse is only standing still," says Eleanor M. Kellon, VMD, owner of Equine Nutrition- al Solutions, in Robesonia, Pennsylvania. "Excess weight also impedes temperature regulation in the heat and makes the heart work harder. Even breathing can be more difficult. The extra weight makes it tougher for the horse during recondition- ing and increases the risk of re-injury." The greatest risk, though, is that of developing the hoof disease laminitis, she says. That's especially true for horses prone to insulin resistance (IR), which is a reduced sensitivity to insulin that makes it harder for fat, muscle, and liver cells to transport glucose out of the bloodstream and store it as the fuel source glycogen. "Horses that become obese can develop a degree of IR that can be detected by sensitive intravenous testing," Kellon says. "Horses on forced inactivity are also going to be less insulin-sensitive than they are when working hard." Is Your Horse at Risk? One of the serious health risks associ- ated with weight gain is insulin dysregu- lation, the umbrella term under which IR, equine metabolic syndrome (EMS), and hyperinsulinemia (high insulin levels in the bloodstream) fall. The condition occurs more frequently in ponies and certain horse breeds, such as Morgans, Warmbloods, and Arabians, says Andrew van Eps BVSc, PhD, MACVSc, Dipl. ACVIM, associate professor of equine musculoskeletal research at the Universi- ty of Pennsylvania's School of Veterinary Medicine (Penn Vet), in Kennett Square. These horses and ponies are at particu- lar risk of developing complications from insulin dysregulation, namely laminitis. If they can't exercise because of their pri- mary lameness problem, they need to be monitored closely for weight gain during their time off, van Eps says. The highest risk category is the horse that's genetically prone to IR but has been in hard work until the time of injury, says Kellon. "The endurance Arabian is the classic example," she says. "Such a horse can gain weight rapidly, show obvious insulin resistance changes on blood work, and even become laminitic within a few weeks if diet is not properly controlled." If you're in doubt about whether your horse has insulin dysregulation, you can request an oral sugar test from your veterinarian, says van Eps. If you're fortunate enough to have a horse that appears unlikely to develop in- sulin resistance, you're not completely off the hook. Our sources point out that even "normal" horses are subject to insulin up- set if they go from hard work to no work without corresponding diet changes. Getting the Rations Right Your greatest weapon against an obese rested horse is diet. The horse's reduced activity level leaves you little choice but to keep an eye on what and how much he's eating. But it's not just a question of re- ducing quantities; it's about ensuring your horse is still getting plenty of nutrition, just with fewer sugars and starches. "For all active horses suddenly put on rest, it's important to adjust the calories to prevent weight gain while preserving adequate protein and vitamin/mineral intake," Kellon says. "Fortunately, this is easily done by moving to a forage-based diet. There's no reason to wean off grain slowly. Just stop it." The exact calorie drop will depend on the situation, Kellon says. "The horse on paddock rest will expend more calories ambling around than while just standing, but can still easily gain weight if fed the same as when being actively worked," she says. "A show hunter or dressage horse will need about a 22% drop in calories, while an endurance or upper level event horse needs about 32% less, even if they are moving around in the paddock." Meanwhile, the IR-prone horse will need even more attention to his calorie intake. "That horse will be on the lower end of the range for calorie requirements because he'll gain weight more easily and will also require a combined sugar (ethanol-soluble carbohydrates, or ESC) and starch intake of no higher than 10% (of the diet)," says Kellon. Unsound and Overweight Extend the foraging time of your easy keeper on layup by offering his hay in a slow feeder. COURTESY HAYGAIN A show hunter or dressage horse (on pad- dock rest) will need about a 22% drop in calories, while an endurance or upper level event horse needs about 32% less." DR. ELEANOR M. KELLON

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