Laboratory rodent

Rodents are commonly used in animal testing, particularly mice and rats, but also guinea pigs, hamsters, gerbils and others. Mice are the most commonly used vertebrate species, due to their availability, size, low cost, ease of handling, and fast reproduction rate.

In the UK in 2015, there were 3.33 million procedures on rodents (80% of total procedures that year). The most common species used were mice (3.03 million procedures, or 73% of total) and rats (268,522, or 6.5%). Other rodents species included guinea pigs (21,831 / 0.7%), hamsters (1,500 / 0.04%) and gerbils (278 / 0.01%).

In the U.S., the numbers of rats and mice used are not reported, but estimates range from around 11 million to approximately 100 million. In 2000, the Federal Research Division, Library of Congress, published the results of an analysis of its Rats/Mice/and Birds Database: Researchers, Breeders, Transporters, and Exhibitors.

Over 2,000 research organizations are listed in the database, of which approximately 500 were researched and of these, 100 were contacted directly by FRD staff. These organizations include hospitals, government organizations, private companies (pharmaceutical companies, etc.), universities/colleges, a few secondary schools, and research institutes. Of these 2,000, approximately 960 are regulated by USDA; 349 by NIH; and 560 accredited by AALAC. Approximately 50 percent of the organizations contacted revealed a specific or approximated number of animals in their laboratories. The total number of animals for those organizations is: 250,000–1,000,000 rats; 400,000–2,000,000 mice; and 130,000–900,000 birds.

Mice are the most commonly used vertebrate species, popular because of their availability, size, low cost, ease of handling, and fast reproduction rate. Mice are quick to reach sexual maturity, as well as quick to gestate, where labs can have a new generation every three weeks as well as a relatively short lifespan of two years.

They are widely considered to be the prime model of inherited human disease and share 99% of their genes with humans. With the advent of genetic engineering technology, genetically modified mice can be generated to order and can cost hundreds of dollars each.

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