An umbilical hernia is a protrusion of abdominal contents through the umbilicus (the umbilicus is the same as our belly button) due to incomplete closing of the umbilical ring after birth. This leaves a small hole in the abdominal wall, allowing the abdominal contents to slip through to form the “bubble” that can be seen and felt in puppies.
Small hernias are generally not a concern and can be left alone, but if large enough, it is possible that a piece of intestine could protrude through and become strangled. Strangulation of the intestine requires immediate veterinary intervention. The larger hernias should definitely be repaired. When a dog is spayed or neutered, it makes sense to have this done at the same time, regardless of its size. Once repaired, it will never be a concern again.
There are two causes of umbilical hernias. One is from trauma such as the umbilical cord being taken down too short or by very rough pulling on the cord by the dam. As much as breeders like to think this is the main cause, it actually only happens in a few instances.
The primary cause is considered to be genetic in nature. It has certainly been found to run in some Maltese lines. The veterinary field recommends not breeding affected dogs, but since the mode of inheritance is unclear, judicious breeding away from umbilical hernias may be more practical at this time.
The inguinal hernia, which is more rare in Maltese, is a hole in the inguinal ring that appears as a skin-covered bulge in the groin area. It can be seen if the dog/puppy is standing up on its hind legs or lying upside down on its back. Often the vet finds the hernia when the puppy has its health examination.