Horses with equine metabolic syndrome (EMS) and pituitary pars intermedia dysfunction (PPID) are at a greater risk of developing laminitis than healthy horses. Dietary changes can help reduce that risk and are one of the most important aspects of keeping affected horses healthy.
Those changes are not necessarily cut and dried—they require planning, sourcing of proper feed products, and management shifts. Teresa Burns, DVM, PhD, Dipl. ACVIM, an associate clinical professor of equine internal medicine at the Ohio State University College of Veterinary Medicine, in Columbus, reviewed how veterinarians can use nutrition and medication to help manage endocrinopathic laminitis cases at the 2017 American Association of Equine Practitioners Convention, held Nov. 17-21 in San Antonio, Texas.
“EMS is prevalent in equine populations, and we’re learning more about how to manage it,” she said. “PPID is also very common.”
All EMS horses and roughly 30% of PPID horses suffer from insulin dysregulation (ID, excessive insulin response to oral sugars, evident as postprandial hyperinsulinemia, fasting hyperinsulinemia, or insulin resistance based on when it occurs), she said. As such, managing ID can help reduce the likelihood of complications—such as laminitis—from arising.
Burns said nutritional EMS and ID management currently involves three steps:
- Reducing dietary nonstructural carbohydrates (NSCs; essentially, the sugar and starch component of the horse’s diet);
- Restricting pasture access until ID is under control; and
- Restricting calorie consumption to encourage weight loss.
She offered practitioners several feeding tips to help achieve these goals.
Aim to keep the total dietary NSC concentration to 10% or less, and base the horse’s diet on low-NSC grass forage. Burns said that while there’s no clinical research to back up the 10% figure, anecdotal evidence suggests it’s an appropriate target. Achieve this by providing most of the horse’s calories via structural carbohydrates—the fibrous portion of plants. Hay typically constitutes the greatest percentage of structural carbs in a horse’s diet. Horses cannot digest structural carbohydrates without the help of billions of microorganisms in the hindgut. This microbial fermentation breaks down fiber into volatile fatty acids, a usable energy form. Nonstructural carbohydrates, on the other hand, are broken down into glucose, which can contribute to obesity and ID. It’s advisable to test hay prior to feeding to ensure low NSC levels; find more information on hay testing at TheHorse.com/19037.
Feed forage at 1 to 2% of body weight. Avoid going above, to encourage weight loss, or below, which could lead to gastrointestinal issues as well as boredom.
Avoid feeding cereal-grain-based concentrates. This means no sweet feeds, corn, oats, and the like, she said. If your horse needs more calories (not all ID horses are overweight), consider a commercially available low-NSC product (such as a high-protein ration balancer) or adding a fat source (such as oil), which produces a lower glycemic response than NSCs.
Reduce or eliminate pasture access, which can be unpredictably high in NSCs. Turn your horse out in a drylot with low-NSC hay access, if possible. If pasture turnout is essential, use a grazing muzzle or strip grazing (cordoning off small areas to graze at a time, using temporary fencing), or turn horses out in the early morning (pasture sugar content peaks in the late afternoon) for a short period.
Consider soaking hay. Burns said soaking hay for 30 to 60 minutes can leach some water-soluble carbohydrates out of hay, but it also removes some important minerals. She advised still starting with a low-NSC hay and working with a nutritionist or your veterinarian to ensure your horse’s mineral needs are being met.
Don’t rely on supplements. While some owners report that certain supplements seem to help their ID horses, Burns said most supplements aren’t backed by research. As such, she advised not basing your feeding program around a particular supplement.
In some cases, veterinarians might prescribe medication for short-term use in cases not responding to dietary management methods. Their goals are to increase insulin sensitivity, mitigate hyperinsulinemia, and encourage weight loss, Burns said. Such products include:
- Levothyroxine (designed to treat low thyroid activity, marketed as Thyro-L); Burns said it’s common to keep the horse on this medication for three to six months, in conjunction with other nutritional management techniques, before tapering the dose; and
- Biguanides (specifically metformin), which are designed to lower blood sugar and improve insulin sensitivity. She said more veterinarians are now prescribing these products to treat ID in horses.
She also encouraged practitioners to treat PPID horses appropriately with pergolide and/or cyproheptadine.
Using nutritional and pharmacologic approaches to reduce the likelihood of endocrinopathic laminitis occurring is an important part of managing at-risk horses.
“Monitor progress over time to be sure it’s being made,” Burns said. “If there’s no progress, change up your protocol.”
Working with your veterinarian and equine nutritionist can help ensure your horse’s nutritional requirements are being met and that you’re managing issues surrounding ID properly.