A hernia is a bulge of tissue or bodily organ that has passed through a tear or defect in a muscular wall. In dogs, the four most common types of hernias include umbilical hernias, inguinal hernias, perineal hernias, and diaphragmatic hernias.

Umbilical hernias are the most common and occur on the midline of the stomach at the belly button. Umbilical hernias pose no real health problems since fatty tissue is usually the only item that protrudes through the opening. These hernias can occur with both male and female dogs.

Inguinal hernias occur where the abdominal muscles meet that of the hind legs. They occur as birth defects or due to injury. These hernias are more serious than umbilical hernias because the intestines can protrude, disrupting the normal digestive process. Replacement of the herniated material and suturing the tear or defective muscle must be done to correct this type of hernia.

Perineal hernias occur due to a weakening of the muscles located beneath the tail on either side of the anus. These hernias usually occur in older dogs and can cause impactions and elimination problems if they are not corrected. Female dogs usually are not affected by this type of hernia.

Diaphragmatic hernias are the most serious type of hernia. A tear or rupture of the diaphragm, the wall of muscle that separates the chest cavity and lungs from the abdomen, can allow the intestines, liver or other vital organs to enter into the chest cavity.
This type of hernia can be congenital or result from an injury. Breathing difficulties, weakness, and intestinal problems can occur and must be surgically corrected. X-rays are the only sure diagnosis of this hernia, but after repair the dog can resume a normal life.