Animal Research and Pain

Debates over the use of animals for research often center on the animals’ experience of pain. Animal welfare regulations require researchers (and instructors who use animals for educational purposes) to report whether the animals they use are subjected to pain and whether it is relieved by medication. When pain-relieving medication is not used during painful procedures, researchers and instructors must justify the reason – for example, by demonstrating that such medications would adversely affect their experiments or lessons. Reporting is not required for mice of the genus Mus and rats of the genus Rattus bred for use in research or for birds and aquatic species other than marine mammals. Here is a breakdown of the reported number of animals used by species, the number of those animals subjected to relieved and unrelieved pain, and the numbers not subjected to pain.

Animal Total Usage With pain, relieved with drugs With Pain, no  pain-relief  drugs No Pain, No Drugs
Guinea Pigs 213,029 63,889 33,652 115,488
Rabbits 210,172 81,303 5,996 122,873
Hamsters 145,895 34,204 48,015 63,676
Nonhuman Primates 71,317 29,413 1,395 40,509
Dogs 64,930 24,710 697 39,523
Pigs 53,260 40,911 770 11,579
Other Farm Animals 38,008 12,884 187 24,937
Cats 21,578 8,595 153 12,830
Sheep 13,271 8,223 65 4,983
Marine Mammals 126 10 0 116
All Other Covered Species 303,107 35,627 6,193 261,287
Total 1,134,693 339,769 97,123 697,801


Source: Annual Report Animal Usage by Fiscal Year, United States Department of Agriculture, Animal and Plant Inspection Service, July 2011; National Institutes of Health Office of Animal Care and Use; USDA Pain Levels;