Definition
An animal model is a species or strain used to investigate biological processes or conditions under controlled conditions. Mice and rats dominate peptide research because of their size, short generation time and the availability of genetically modified strains, such as diet-induced obese mice or knockout lines lacking a specific receptor. Other models include zebrafish, rabbits, pigs and non-human primates. Animal studies require ethical review, follow the 3Rs principles of replacement, reduction and refinement, and should be reported under the ARRIVE guidelines. Differences in metabolism, receptor distribution and lifespan limit translation, so findings in animal models are evidence about the model and require confirmation in humans.