Animal Health Concern : Sheep Industry, Big Birds

by Food and Drug Administration (FDA)

(Page 3 of 3)

Sustaining the Sheep Industry

The U.S. sheep population has been steadily decreasing since the 1940s — from its peak at 56 million in 1942 to less than 7 million in 2002, says the USDA.

The lack of approved drugs for sheep is one factor contributing to the decline, says Oeller. The sheep industry loses about $45 million worth of sheep each year from diseases for which drugs are unavailable.

In addition to disease-treating drugs, American sheep ranchers are lacking another important tool: "the capability to manipulate reproduction," says Oeller. In other countries, such as Australia, sheep ranchers can use progesterone implants to manipulate the reproductive cycle. "This gives them spring and fall breeding of sheep, while we are limited to one breeding season in this country," says Oeller.

In response to the industry's need, the Minor Use Animal Drug Program is currently researching a vaginal progesterone for sheep and goats.

Big Birds

Powell Anderson, D.V.M., splits his time between his veterinary hospital in Dillwyn, Va., and his ostrich ranch next door. An ostrich breeder since 1996, Anderson sees the future of agriculture and the rebirth of small farms in businesses like his. It's a healthy and environmentally sound alternative to some other forms of animal food production, says Anderson, who doesn't use growth hormones or antibiotics in his birds.

Anderson sells the low-fat ostrich meat, which he compares to filet mignon in taste, to local restaurants. He incubates the fertile eggs during mating season and sells them for food in the mating off-season. "You can't taste the difference between scrambled ostrich eggs and chicken eggs," says Anderson, who plans to be eating ostrich eggs for a very long time. "The females lay eggs for 40 years and live to be 70."

With no FDA-approved drugs to treat ostriches, Anderson must rely on his own knowledge of veterinary medicine, an ostrich encyclopedia, and trial and error. Luckily, his birds have been pretty healthy, he says, but when one is sick, it goes down quickly. "You can't tell they're sick until they're almost dead."

Sharyn Felts, owner of one of the largest emu ranches in California, also considers herself blessed that most of her 800 emus have been disease-free. The six-foot tall, 150-pound birds, second in size only to ostriches, are very hardy, she says.

In addition to their meat, the emus are valued for their oil as an emollient used in moisturizers, shampoos and soaps. Their feathers are used by fishermen to tie flies, and their hides serve the leather industry. The dark green emu eggs are prized by artists, who carve or paint them.

Off-Label Use and Medicated Feed

The Animal Medicinal Drug Use Clarification Act (AMDUCA) of 1994 eased the scarcity of animal drugs somewhat by allowing veterinarians to use approved animal and human drugs "extra-label," or "off-label." This means that under certain circumstances, veterinarians can use drugs approved for other species, for other diseases and conditions, or at different dosage levels from those listed on the drug label.

This flexibility of drug use may help to ease animal suffering, but the different metabolisms of some species make the effective dosage a guessing game, says Oeller. The benefit of having a drug approved for a specific species is that "you can count on a specific withdrawal time and know the correct dosage," Oeller says.

Although the AMDUCA allows off-label use of drugs, it prohibits off-label use in animal feed. But medicated feed often is the best route of getting a drug into certain animals, such as fish and game birds. Injecting an individual fish with a drug may be feasible for some types of brood stock, says MacMillan. "But such injection is not feasible for a large population of farm-raised aquatic animals such as trout, catfish, tilapia or bait fish."

Bill Mac Farlane, who owns one of the nation's largest pheasant farms, located in Janesville, Wis., says he needs medicated feed for his pheasants and other game birds, particularly to treat coccidia, a deadly parasite that infests the intestines. The alternatives to medicated feed don't work very well, says Mac Farlane. It's not practical to catch each bird and give them a shot every day, nor is adding a drug to the water effective. "They don't like the taste of the medicated water. They drink out of the puddles after a rain instead, so they don't get their medication."

To meet the requirements of the fish and bird industries, the Minor Use Animal Drug Program has shifted much of its focus to the approval of medicated feeds, says Oeller. The program is currently testing several medicated feeds for pheasants to treat bacterial infections and coccidia and other parasites, and Mac Farlane's pheasant farm is participating in the study trials.

Keeping Animals Healthy

Currently, the Minor Use Animal Drug Program is working on more than two dozen projects, and continues to review requests for treatments to keep animals healthy. Among the active projects are drugs to treat diseases in game birds, goats, sheep, deer, rabbits, bees, and a variety of fish.

"It's never a good idea to have unhealthy animals," says Oeller. "You don't want the risk of products from unhealthy animals entering the human food supply, you don't want them exposing other agricultural animals to disease, and you don't want wildlife transporting disease-carrying ticks into areas frequented by people. Both from a public health and an animal welfare standpoint, you're better off having healthy animals."

Few Drugs for Wild Animals, Pets

Few FDA-approved drugs are available for animals considered to be "minor species." These include wildlife, exotic animals, endangered species, and pets such as birds, rabbits, reptiles, and guinea pigs.

Veterinarians who treat these animals often must rely on unapproved animal drugs or drugs approved for humans or other animals. Sometimes a drug approved for one animal can be used with confidence in another animal with a similar metabolism, says Stephen F. Sundlof, D.V.M., Ph.D., the director of the FDA's Center for Veterinary Medicine. "But when it comes to exotic animals, there is no formula for extrapolating between one species and another — it's a big gamble."

More animal drugs could be available if the Minor Use and Minor Species Animal Health Act is passed by Congress. The "MUMS bill" would establish several new ways to lawfully market new animal drugs while maintaining the rigorous public safety requirements of the FDA.

About the Author

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