The hernia shows up as a large soft swelling on one or both sides of the anus. Once the rectum has lost its muscular support it stretches into the space created by the tear. Eventually faeces can impact in this stretched rectal sack causing staining and difficulty passing motions. It is also possible for the bladder to occasionally move backwards into the hernial space and become entrapped. When this occurs the dog will strain to urinate generally without success.

Perineal hernias are almost exclusively seen in older entire male dogs. The underlying process that leads to rupture of the pelvic muscles is unclear however conditions which cause straining may be involved. These include enlargement of the prostate gland, constipation and some tumors around the anus. An increase in the level of male sex hormone (testosterone) may also be involved. Some tumors of the testicles which produce higher levels of testosterone have been associated with an increased incidence of perineal hernias.

Surgery is the only effective treatment for these hernias however some dogs can be managed using drugs to keep the faeces soft. The traditional surgical method has been to pull the damaged muscles together however there is relatively high rate of long term failure with this method. A newer method where the internal obturator muscle which lies on the floor of the pelvis is shifted to act as a patch over the damaged area is proving to have a much higher success rate. Castration is also recommended by many veterinarians.