November 16, 2012

An experimental drug discovered by entomologists doing research on biological insect control substances now holds some promise as an effective treatment for laminitis.

Veterinarians at the University of California, Davis, School of Veterinary Medicine will conduct the first clinical trial of the anti-inflammatory drug known as t-TUCB after it was used to treat a horse that they thought would have to be euthanized.

A paper on this case has been accepted for publication by the peer-reviewed Journal of Veterinary Anaesthesia and Analgesia. The paper is expected to be published in the journal's February 2013 issue, but journal editors have allowed the authors to disclose their findings ahead of publication.

"This is an unusual step for us to announce this so far in advance, but because euthanasia is often the only way to alleviate pain in severe laminitis, we felt that it was important to let the veterinarians and horse owners know that this compound has shown potential as a treatment," said Alonso Guedes, an assistant professor in the School of Veterinary Medicine.

In his paper, Guedes reports the case of a 4-year-old Thoroughbred mare named Hulahalla that developed laminitis. The horse had been retired from racing due to a tendon injury and donated to the UC Davis School of Veterinary Medicine, where she was used in a study focused on healing tendon injuries using stem cell treatments.

Hulahalla's laminitis was treated with conventional therapies including cold immersion, antibiotics, leg wraps, and two commonly used non-steroidal drugs intended to reduce inflammation and relieve pain. Her condition only got worse and eventually was spending most of the day lying down.

Before resorting to euthanasia, Guedes contacted UC Davis entomology professor Bruce Hammock about trying t-TUCB, which belongs to a group of anti-inflammatory compounds Hammock discovered 40 years ago. Hammock had broadened the scope of his research and found the compounds were effective in relieving inflammation, discomfort and pain related to nervous system disorders in mice and rats. The drug, however, had not been used in a mammal as large as a horse.

The veterinarians administered the experimental compound intravenously early on the eighth day of Hulahalla's illness. After receiving the first dose, the horse remained standing in the stall most of the day, became interested in her surroundings and walked voluntarily.

The mare's demeanor, posture and mobility continued to improve over four days of treatment, and her blood pressure gradually returned to normal. No adverse affects from t-TUCB were observed, and Hulahalla has remained laminitis-free for a full year.

The survival rate for laminitis is estimated to be only 25%. Very few surviving horses return to their previous levels of activity, and laminitis often reappears.