Laminitis vaccine shows promise but funding proves difficult

RED DEER — Researchers have found a solution for equine laminitis but are waiting for a white knight to ride up with a bucket of cash to develop it.

Equine lameness, which is also known as founder, affects only three to five percent of horses. However, it is usually career ending and often life ending for those that develop the condition, said Dr. David Wilson of the University of Saskatchewan’s Western College of Veterinary Medicine.

“It is a very severe condition if it affects your horse,” Wilson said.

The racehorse Secretariat and Kentucky Derby winner Barbaro both developed laminitis and were euthanized.

Secretariat developed laminitis from something in the diet, and Barbaro developed laminitis after shattering his leg in the Preakness and putting weight on the other feet.

The vaccine developed at the university protected slightly more than 80 percent of the horses in the study, but it has been difficult finding a drug company willing to manufacture it.

Horses on a hay diet are not prone to laminitis, and horses on drier pasture grasses, such as those in Saskatchewan, are not likely to develop the disease.

“It would be a valuable vaccine for horses on lush grass or have the possibility of grain overload,” Wilson told the recent Alberta Horse Industry Conference.

“If you are in an area where grass founder is a common scenario, then I would look at it as an annual vaccination,” said Wilson.

Most laminitis cases result from gastrointestinal upset, whether it is grain overload or founder on grass pasture.

“Grass founder is the same as grain overload,” he said.

“During certain periods of time, with certain grasses, especially rye grasses, the highly digestible carbohydrates within the grass goes up and down. When highly digestible carbohydrates are high in the grass and horses grazing on them, they can overload, while just grazing.”

Wilson said the hoof wall is a complex structure that dovetails together. Tissues rip apart and detach from the bone when the hoof begins to fail, which creates a painful condition that can often cause the feet to rotate or drop off.

Australian researchers found that laminitis in the early stages can be controlled by submerging the horse’s feet up to their knees in ice water to lower the hoof temperature to 3 to 5C.

The horse will still develop the stomach upset component of the disease but not hoof lesions.

“The ice bath applied prior to the development of the lesions on the foot works really well,” said Wilson.

American researchers found that horses subjected to grain overload will cause laminitis, but a pre-treatment with the antibiotic virginiamycin will prevent its development.

Horses with overload are continually bombarded with exotoxins.

“If the exotoxins overload the body’s ability to deal with it, then the horses are more likely to develop a problem.”

The Saskatoon researchers wanted to evaluate the efficacy of an exotixin vaccine to prevent overload-induced laminitis.

A control group of five horses was not given vaccines, while a second group of 24 horses was vaccinated three times a week at three-week intervals.

All horses were subjected to carbohydrate overload four weeks after the last vaccination.

Twenty horses remained sound and four vaccinated horses developed a degree of lameness but not as severe as those with no vaccine.

The non-vaccinated horses de-veloped full-blown laminitis and were humanely euthanized.

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