June 2, 2020

The U.S. Food and Drug Administration is revising its estimates of the numbers of cats and horses in the United States, based on information from the American Veterinary Medical Association (AVMA) and the United States Department of Agriculture (USDA). The population estimates from both species have decreased since the last estimate, made in 2014.

Population estimates are important for helping to determine potential eligibility for drugs to be used for “minor uses.” A “minor use” is the intended use of a drug in a major species (horses, dogs, cats, cattle, pigs, turkeys, and chickens) for a disease or condition that occurs infrequently or in limited geographic areas and in only a “small number” of animals annually. Such “small numbers” are set through rulemaking, but accurate population estimates have an effect upon whether a particular disease or condition qualifies as a minor use. In essence, if the population decreases, the likelihood of a particular disease or condition being considered a minor use increases.

The Minor Use/Minor Species  program is part of the FDA’s continuing mission to assure that safe and effective animal drugs are available to meet the health needs of a wide range of diverse species. New animal drugs that are intended for minor uses in major species or for use in minor species (MUMS) qualify for certain incentives.  These include MUMS Designation, Conditional Approval, and waivers from user fees.  MUMS designated drugs are eligible to receive exclusive marketing rights and grants to support product development and approval. Conditional Approval permits quicker access to the marketplace.

“Minor species” are all animals other than humans that are not one of the major species. They include animals such as zoo animals, ornamental fish, parrots, ferrets, and guinea pigs. Some animals of agricultural importance are also minor species. These include sheep, goats, catfish, game birds, and honey bees, among others. 

The FDA relied on the most recent (2018) AVMA survey to revise the population estimate of cats in the U.S. downward from 74 million to 58.4 million, a 21 percent decrease. For horses, the FDA utilized both the AVMA survey and information from USDA’s periodic surveys of farm animal populations to estimate the U.S. horse population at 3.8 million. This is a 22 percent decrease from the previous estimate of 4.9 million horses.  

For more information:

• Minor Use/Minor Species
• FDA Awards Grants to Help Fund Studies for Drugs for Minor Uses/Minor Species