Domestic cat Felis catus

The domestic cat is a small obligate carnivore kept worldwide as a companion and, historically, as a rodent controller. Its clinical medicine follows from that dietary specialisation. Cats have higher requirements than omnivores for protein, arginine, taurine, methionine and cystine, arachidonic acid, niacin, pyridoxine and vitamins A and D, because they cannot make enough of them from plant precursors; hepatic glucokinase activity is minimal to absent and gluconeogenesis from amino acids runs constantly, so dietary protein is a working fuel rather than a surplus. The same hypercarnivorous ancestry left a drug-handling defect that matters at every consultation: the gene for UDP-glucuronosyltransferase 1A6, the main phenol-detoxifying enzyme in mammals, is a pseudogene in the cat and other felids, and the resulting slow glucuronidation explains feline sensitivity to paracetamol and aspirin and the slow clearance of both. Doses safe in a dog are not transferable. Life expectancy at birth in a United States primary-care population of 2.39 million cats was 11.18 years, females outliving males by close to a year. Resting heart rate is high, 120 to 140 beats per minute, with respiration of 16 to 40.