Animal Health

Pet Medicines
by Food and Drug Administration (FDA)

Nearly a century ago, farmers had a medicine chest of products to "cure" their animals, with names such as Lee's Gizzard Capsules, Liquid Hog Medicine, and Kow-Kure. The gizzard capsules, made with nicotine, were advertised to get rid of worms in turkeys. Liquid Hog Medicine, which contained lye, was for treating diarrhea in pigs. And Kow-Kure, whose exact ingredients remain a mystery, purported to prevent miscarriages in cows.

No one knew whether these products were actually safe or effective, but all were allowed on the market under the federal drug laws at the time.

Such products went by the wayside as Congress passed stronger drug laws, and today, the regulation of animal drugs closely parallels the regulation of human drugs. Like human drugs, all animal drugs must be approved by the Food and Drug Administration before being allowed on the market. The FDA's Center for Veterinary Medicine (CVM) is responsible for regulating drugs and food additives used for animals - both food-producing animals and family pets.

To date, the CVM has approved nearly 700 drug products for use in 97 million cattle, 59 million pigs, 8.8 billion chickens, 272 million turkeys, 7 million sheep, and millions of other food-producing animals in the United States. In addition, more than 700 approved drug products are available to maintain the health of America's 60 million pet dogs, 75 million pet cats, and 5 million horses.

The FDA employs more than 100 veterinarians, most of them within the CVM. These animal experts - plus chemists, animal scientists, toxicologists, microbiologists, and other professionals - are committed to protecting animal and human health throughout the United States. They evaluate the benefits and risks of proposed veterinary products before permitting them to be marketed; monitor the use of products after they are on the market; take legal action, if necessary, to enforce laws; and conduct research to support the FDA's science-based decisions.

The Evolution of Animal Drug Law

Animal feed and drugs have been regulated for as long as human food and drugs. When Congress passed the Pure Food and Drugs Act in 1906, it introduced the regulation of food and drugs in interstate commerce for "man or other animals."

But the 1906 act gave the FDA limited powers to protect consumers against adulterated and misrepresented food and drugs, says FDA Historian John Swann, Ph.D. "It was against the law to make a false or misleading claim for a product, but it could be difficult to prosecute offenders, especially after the law was amended in 1912 to require that fraudulence be proven to establish misbranding," he says. "And violations of the law were misdemeanors with fines that could be as high as $300 along with jail terms, but more often these were considerably lower. However, the violative products could be seized and destroyed."

The 1906 law did not give the FDA authority to approve products before they were marketed. When the Federal Food, Drug, and Cosmetic Act (FD&C Act) was passed in 1938, it strengthened the FDA's powers. For the first time, manufacturers were required to show evidence that their products were safe before they could sell them.

The decades after the new law went into effect brought the development of many new animal drugs and medicated feeds. The veterinary regulatory arm of the FDA evolved from a small branch in 1953 to a larger division in 1959. Government officials, recognizing the importance of food-producing animal health to the welfare of the country, elevated the division to the bureau level in 1965. In 1984, the Bureau of Veterinary Medicine (BVM) changed its name to the Center for Veterinary Medicine.

Cancer-Causing Chemicals in Food Animals

Congress amended the Federal FD&C Act to include a series of laws addressing food additives in 1958 and color additives in 1960. These laws gave the FDA tighter control over the growing list of chemicals entering the food supply and gave manufacturers the responsibility to establish the safety of their products. The laws included a provision, known as the "Delaney Clause," which established that no food or color additive could be deemed safe - or given FDA approval - if found to cause cancer in humans or animals.

In 1962, the Delaney Clause was modified to permit the FDA to approve the use of carcinogenic compounds in food-producing animals if certain conditions were met. "The FDA felt that food-producing animals could be exposed to carcinogenic drugs and not necessarily pass cancer-causing chemicals on to humans," says Woodrow Knight, Ph.D., director of the CVM's Division of Production Drugs.

The modification to the Delaney Clause is known as the "Diethylstilbestrol (DES) Proviso," named for a hormone approved in 1954 to promote growth in cattle and sheep. DES had also been approved much earlier in humans. It was thought to prevent miscarriages in women, but the hormone later was linked to vaginal cancers in the daughters of women who were treated with the drug during pregnancy.

Under the DES Proviso, the FDA could approve a carcinogen for food animal use if the concentration of any residue remaining in the edible tissues was so low that it presented an insignificant risk of cancer to consumers.

But measuring drug residues was a problem. Standard tests at that time were not very sophisticated, and regulators were concerned that drug residues in foods might exist in dangerous levels and just couldn't be measured.

Using advances in analytical chemistry, FDA scientists developed techniques to measure minute concentrations of residues, says Knight. "They were able to measure parts per billion or even per trillion." These techniques led to a 1987 regulation called the Sensitivity-of-Method procedures, or SOM. The regulation defines an insignificant risk of cancer as a 1 in 1 million increase in risk, and spells out how to measure the residue concentration.

Although DES was banned for use in people and animals in the 1970s, the DES Proviso remains in effect. SOM procedures are used to determine acceptable residue concentrations of new animal drugs in food produced from animals.

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.