Orchitis is generally associated with an inflammation of the epididymides, organs that serve as a storage canal for the sperm. In dogs and cats, the bacteria Brucella and Escherichia coli, the fungus coccidiomycosis and blastomycosis and the distemper virus are the main causes of orchitis. Animals with a history of urinary tract infections have higher chances to develop orchitis. Symptoms of orchitis in cats and dogs also include excessive licking of the testes and lethargic behavior. The best way to prevent this condition is castration.
Guinea pigs, mice and other rodents can develop orchitis after being infected with Streptococcus, Pasteurella multocida and other pathogens. In Africa, the monkeypox virus attacks rodents as well as monkeys and rabbits, causing an infectious disease that can cause from cutaneous lesions to death. The virus is also responsible for the development of orchitis in affected animals.
Ungulates or animals with hoofs, such as horses, bulls and camels, can also develop orchitis. The bacteria Streptococcus equi subspecies zooepidemicus can cause a inflammatory disease called "alpaca fever" and orchitis in alpacas (Vicugna pacos). Among other pathogens, the bacteria Salmonella enterica subspecies diarizonae serovar also can cause orchitis in rams as well as infection in other organs, such as lungs and liver.
Unlike mammals, birds and reptiles have their testes located inside their bodies. As the characteristic swelling of the organs cannot be observed in infected animal, the diagnosis of orchitis in birds ans reptiles often involves blood sampling, endoscopy and other laboratory procedures. Birds and reptiles have a single organ called cloaca to excrete their intestinal and urinal wastes. Cloacal infections are often the main cause of orchitis in reptiles and birds.