Very little is known about male infertility in the dog. The causes of infertility are divided into two main groups, congenital infertility and acquired infertility. Congenital infertility is caused by genetic (chromosomal) abnormalities and is present at birth. Acquired infertility develops during the dog's lifetime. Infertility in male dogs is diagnosed by a good medical history, including breeding management, and a physical examination.