Common hernias in dogs include perineal hernias, which are located around the tail and rectal region. They almost always occur in non-neutered male dogs. First they will present as swelling around the tail, sometimes worse initially on the right before the left becomes affected. Eventually perineal hernias will cause difficulty with defecation and occasionally problems with urination. They are treated with a muscle flap procedure to close the hernia. It is common to perform surgery on the left and the right sides at the same time as well as to neuter the dog. Perineal hernias occur in cats, but can be missed as they cause constipation which is attributed to a more common problem of megacolon in cats.
Diaphragmatic hernias occur in dogs and cats and the most common cause is vehicular trauma. The diaphragm is a sheet of muscle that separates the chest and abdomen and performs the dual function of facilitating breathing as well as keeping abdominal contents separate from the chest. Surprisingly, it can be difficult if not impossible to tell from a physical exam if a pet has a diaphragmatic hernia. A chest X-ray is necessary in most instances to achieve an accurate diagnosis. It can be surgically corrected, resulting in a very good prognosis.
Inguinal and abdominal hernias occur in dogs and occasionally in cats. Inguinal or scrotal hernias in male dogs are the most likely to cause problems via intestinal blockage. We recommend repairing all inguinal hernias in male dogs (including neutering at the same time). In females, the hernias are usually larger and intestinal blockage is much less likely. The hernia will cause problems once it becomes large enough to touch the ground and cause skin damage.