Tendon Repair Drug Approved

The FDA has approved the first and only medication designed to improve the quality of repair to injured or "bowed" tendons. Bapten (beta-aminopropionitrile fumarate), manufactured by Boehringer Ingelheim Vetmedica, is labeled for use in treating superficial digital flexor tendon injuries. While it does not shorten the time needed for recuperation, it does promote proper tendon healing and repair that allows for a "more athletically functional repaired tendon" when the healing process is completed.

After more than seven years of study, including FDA-regulated field trials at various sites and universities across the country, Bapten now is available to the general public through their veterinarians.

Collagen is what the body produces to repair tendons. According to the research, severe injury to the equine superficial digital flexor tendon usually produces a scar composed of randomly aligned and cross-linked collagen fibers (like dropping a box of toothpicks that land every-which-way). The repaired tendon often is weaker and becomes thickened and shortened, resulting in decreased motion. By inhibiting the cross linking of newly formed collagen, Bapten allows for the fibers to align more naturally in parallel rows. The treatment must be conducted along with a carefully controlled and monitored exercise program.

Officials with Boehringer Ingelheim and researchers who worked closely with Bapten are quick to point out that the drug by itself is not a miracle cure.

"The drug will do its job, but by itself, that won't be enough," said Ronald L. Geneovese, DVM, of Randall Veterinary Clinic in Warrensville Heights, Ohio, and one of the leading researchers for Bapten. "Tendon treatment plus tendon loading management (controlled exercise) is the key to successful tendon recovery in horses."

According to Genovese, successful rehabilitation will hinge on a close partnership between veterinarians, horse trainers, and owners in managing a controlled loading (exercise) program that can last anywhere from six months to a year or more. Recovery won't happen, he pointed out, if a horse is brought back too soon.

"It means a lot of time and patience, and that can be especially hard for trainers, who sometimes may think that if a horse isn't racing, it isn't making money and isn't worth having around," said Genovese. "The good news, however, is that we now have a way to return at least some performance horses back to competition."

To ensure that the healing process and scar remodeling are properly occurring, industry experts familiar with Bapten are recommending the use of ultrasonography not only to diagnose the type and severity of a tendon injury, but to monitor tendon healing and remodeling.

"Ultrasonography allows veterinarians to determine how much exercise a horse can handle at a given period of time during the recovery period," said Virginia Reef, DVM, of the Department of Clinical Studies at the University of Pennsylvania's New Bolton Center, who also researched the drug. "We have to realize that just because the tendon looks good clinically, internally the healing may be inadequate to withstand rigorous exercise. After several months, the injured tendon usually appears fine cosmetically, but the ultrasound examination will reveal that it clearly isn't healed and that much more time is needed for adequate tendon healing to occur before returning the animal to competition."

It is recommended that Bapten be injected directly into the lesion within the injured tendon. Injections are placed medially, laterally, and in the palmar surface of the tendon at several levels and directly into the tendon lesion (up to 50 injections per treatment). The administration is repeated every other day for a series of five injections beginning approximately 30 days after the initial injury.

For further information on Bapten, contact Boehringer Ingelheim Vetmedica at 800/821-7467 or see your veterinarian. (For additoinal information on Bapten, see The Horse of September 1996, page 31, or The Horse Interactive web site at www.thehorse.com.

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