When Wild Animals Get Sick: Drugs

by Food and Drug Administration (FDA)

"Come on sweetie. Wake up."

Mitchell Bush, D.V.M., is urging his sedated patient awake following exploratory surgery for an abdominal mass. His patient, a 35-pound female maned wolf from South America, has ovarian cancer.

She slowly comes to as her keeper carries her back to her cage. It looks as if she will survive the surgery.

Bush and his staff are pleased. Even though surgery on rare and exotic animals is fairly routine at the National Zoological Park's Conservation and Research Center in Front Royal, Va., it's always risky, considering virtually no anesthetics, antibiotics or other drugs are approved for these animals. Instead, veterinarians like Bush rely on personal experience, published data, and word-of-mouth from other veterinarians to use animal and human drugs already on the U.S. market or approved for use in foreign countries.

"We're dealing with a lot of unknowns," says Bush, who is the center's chief veterinarian. "There's hardly any drug on my shelf that's approved for these animals."

Congress wants to change that. This year, as mandated under the Animal Drug Availability Act of 1996, the Food and Drug Administration plans to propose measures that will encourage drug companies to seek approval of drugs for minor species and minor uses in major species. The purpose is to alleviate the scarcity of safe and effective drugs for these animals.

A minor species is defined as any animal other than dogs, cats, cattle, horses, pigs, chickens, and turkeys. Minor use of a drug includes drugs used to treat minor species and used to treat rare diseases in major species or diseases in major species confined to certain geographic areas. Examples of two drugs FDA approved recently that fall into the "minor use" category are Antizol-Vet (fomepizole) as an antidote to antifreeze intoxication in dogs — usually limited to dogs in the Northern states — and Imizol (imidocarb dipropionate), an antiparasitic for babesiosis in dogs.

FDA's anticipated proposals, if adopted, could benefit a wide range of animals, including zoo animals; common U.S. wildlife, such as deer, fox, squirrels, and raccoons; minor species farmed for food, such as game birds and goats; and many pets, such as birds, fish, ferrets, guinea pigs, and hamsters.

FDA believes that increasing the availability of drugs for these kinds of animals will not only benefit them but humans, as well. "Organisms capable of causing disease in minor species are not confined to such species," a work group in FDA's Center for Veterinary Medicine wrote in a preliminary set of proposals. "It is clearly in the public interest to treat such diseases in minor species before they are transmitted to people or other animals."

To increase the number of approved drugs for minor species, FDA plans to propose measures that would encourage new drug development, more clinical trials both of new drugs and of drugs already approved for major species and humans in minor species, and the submission of new animal drug applications (NADAs) for agency review.

Linda Wilmot, D.V.M., veterinary medical officer and team leader in FDA's Center for Veterinary Medicine, says some of the measures expected to be proposed would follow closely those allowed under FDA's Orphan Products Development Program. The program encourages drug companies to seek approval of drugs for rare human diseases and conditions by offering companies help with study design and by giving financial incentives, such as tax relief, grants, and extended exclusivity periods. In the past, drug companies were reluctant to develop drugs for "orphan diseases" because the small patient populations made investment in research unprofitable. The same holds true for rare animals and rare animal diseases in the current veterinary market, Wilmot says.

Other potential measures, based partly on public comments FDA received in response to a June 1997 Federal Register request and ideas floated by FDA's work group, could be more far-reaching and innovative, she says.

These proposals might, for example:

Encourage drug companies to seek drug approvals by offering them financial incentives — for example, tax credits and longer periods of protection from generic competition

Create a fair marketplace by reducing sale and use of unapproved animal drugs. According to the FDA work group, companies that might consider seeking agency approval for drugs for minor use are now reluctant to invest in the process because they cannot always be assured of protection from competition with unapproved drugs. The work group said FDA's enforcement work needs more resources.

Many of the potential proposals would require congressional action — for example, allocating additional funds for animal drug research grants and drafting new legislation to provide tax credits and prolong the period of drug exclusivity. Other measures, such as revising a regulation, could be accomplished by FDA through rule-making.

Successfully increasing the number of approved drugs for minor species or minor use will likely depend on the adoption of more than one proposal, Wilmot says.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.