laboratory animals types

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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3733029/
The laboratory rat is an inevitable part of today's biomedical research. They are recognized as the preeminent model in numerous fields, including neurobehavioral studies, cancer and toxicology.[1] It is difficult to evaluate the number of animals employed in scientific experiments every year. An estimation suggests some dozens of millions per year, being 15 million in the United States, 11 million in Europe, five million in Japan, two million in Canada and less than one million in Australia. Almost 80% of the experimental animals are rodents that include mice, rats, guinea pigs and others (10% are fish, amphibians, reptiles and birds). A third group includes rabbits, goats, bulls and in smaller amounts, dogs, cats and some species of primatess.[2] They substitute the human being as an experimental object in scientific researches. Among the rodents, rats are the mostly used animals for experimental purposes (accounting for approximately 20% of the total number of mammals used for scientific purposes), followed by mouse, rabbit, dog, pig and primate, especially for in vivo studies. About 85% of the articles in Medline, and 70.5% of the articles in Lilacs, employed rats and mice.[3] All over the past 80 years, rats have been utilized in investigations in almost every aspect of biomedical and behavioral research. A recent publication dealing with biomedical research applications lists the following areas of biomedical investigation as ones in which the rat is widely used and is particularly useful in: Toxicology, teratology, experimental oncology, experimental gerontology, cardiovascular research, immunology, dental research immunogenetics and experimental parasitology.[4] The rat is also the most widely used laboratory mammal in behavioral studies, for which, incidentally, the mouse is not well suited. Rats have traditionally been the animal of choice in much nutritional research, although it should be noted that their natural habit of coprophagy may limit their suitability for certain of these studies.