Heat is probably the greatest offender, especially in stallions, bulls, and boars. Rams are less affected because they are fall breeders. Excessively cold temperature can also limit a male's fertility, and freezing of testicular tissue results in sterility. Temperature-induced changes are diagnosed on history and BSE results. Therapy involves reversing the initial insult.
Infectious agents are common problems, especially venereal diseases.
Brucellosis is a venereal disease that causes epididymitis, orchitis and azoospermia. Brucellosis is primarily a problem in cattle, sheep and dogs and usually requires euthanizing affected animals. Other bacterial infections are common in stallions and stud dogs. Therapy is as indicated by the culture and sensitivity. Neoplasms are rare in domestic animals except in the dog where Sertoli cell tumors and seminomas are seen.