Danger time for insulin-resistant horses

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Insulin-resistant horses are entering the dangerous season of spring grass-growth in the southern hemisphere, where their risks of developing laminitis are greatest.

Washington State University veterinarians, writing in the latest edition of Equine News, have offered advice for the management of insulin resistant horses.

While Insulin resistance can trrgger type 2 diabetes in people. In horses, it can lead to equine metabolic syndrome (EMS).

It is not uncommon in horses, and has been gaining more recognition because of the level of awareness and epidemic of people living with type 2 diabetes.

"We have diagnosed five or six horses at the Veterinary Teaching Hospital during the past year," said Dr Nicki Wise, a WSU second-year equine medicine resident.

"Most presented with chronic laminitis (also referred to as founder), which is the one of the biggest problems for horses that have EMS."

Laminitis is a painful condition in the hoof that can be life-threatening if severe enough. Beyond chronic laminitis, a horse's appearance may raise suspicions of EMS.

"Often, horses with EMS have abnormal fat deposits over their neck, rump, tail, and eyes," she said.

"The disease is closely related to Cushing's disease. Technically it is different, but a lot of the signs are the same. Generally, the disease is not life-threatening, but it will probably shorten their lifespan if these horses are not managed properly."

Ponies, Arabians, and Paso Finos are among the common breeds that the condition is found in, but any horse can suffer from it.

EMS also tends to occur in middle aged to older horses, and those who are obese and have a sedentary lifestyle.

"We don't know if obesity leads to insulin resistance or if insulin resistance results in obesity," Dr Wise said. "We don't know which comes first."

To confirm an EMS diagnosis, veterinarians look at clinical signs, perform a physical examination, and take a blood test to measure serum insulin levels.

"The blood test is easy and inexpensive, and can differentiate between insulin resistance and Cushing's disease," Dr Wise said. "If insulin levels are high, the horse probably has EMS."

There is no cure for horses with EMS, although they can benefit from consuming a diet consisting mostly of grass hay that has a low glycemic index. Glycemic index is the measure of a food's effect on blood sugar.

"No grain or treats like carrots should be fed. Several companies offer commercial pelleted feeds for horses with insulin resistance, which might be an option for picky horses. But always check with a veterinarian before switching feeds."

Regular exercise is also part of a management plan for many horses with EMS, but this requirement can be hard to meet if a horse is suffering from chronic laminitis.

"If there aren't any lameness issues, exercise is one of the best things that a horse can do," Dr Wise said.

"When switching feed, horses can lose muscle rather than fat, and exercise can help with this considerably. Owners need to understand what condition their horse is in and monitor it so the horse does not waste away. Owners that stick to the changes have horses that feel better, are generally more active, and have fewer cases of laminitis."