Umbilical hernias in dogs do have a genetic component. Research published in the Veterinary Record describes the defect as a “polygenic threshold character,” meaning multiple genes contribute to the risk rather than a single on-off switch. A major gene likely plays a central role, but its expression depends on the broader genetic background of the breed. That said, genetics isn’t the only cause. Umbilical infections and traumatic cord separation at birth can also produce the same defect.
How the Defect Develops
During early embryonic development, a segment of intestine temporarily pushes into the umbilical cord. This is normal. Later in gestation, the intestines withdraw back into the abdomen, the cord’s blood vessels are all that remain, and the opening in the abdominal wall (the peritoneal ring) seals shut, leaving the familiar navel scar.
An umbilical hernia forms when that abdominal wall doesn’t close completely. The sealed peritoneal ring may be intact, but the overlying muscle and tissue remain defective, allowing fat or even loops of intestine to bulge outward into a small sac beneath the skin. In genetically predisposed dogs, the signals that direct this closure process are less reliable, which is why the problem clusters in certain breeds and family lines.
Breeds at Higher Risk
Weimaraners, Pekingese, Basenjis, and Airedale Terriers are overrepresented in umbilical hernia cases. The fact that certain breeds show consistently higher rates is itself strong evidence for a hereditary basis. If you’re buying a puppy from one of these breeds, asking the breeder about hernia history in the parents and previous litters is reasonable.
Breeding Considerations
Because umbilical hernias are heritable, breeding decisions matter. The Australian Shepherd Health & Genetics Institute offers guidelines that apply broadly across breeds: if a hernia was large enough to need surgery, that dog should not be bred. Dogs with minor hernias or hernias that resolved on their own are considered to carry the trait as a fault, and breeders should avoid pairing them with mates from lines that also have hernia history.
Full and half siblings of affected dogs carry risk too, even if they appear normal. Males with hernias should not be used extensively at stud. The logic is straightforward: because multiple genes are involved, dogs that look unaffected can still pass the trait to offspring when matched with another carrier. Breeding away from the trait across generations is the recommended approach rather than simply removing the most obviously affected individual.
One distinction worth noting: hernias in puppies are almost always congenital and potentially hereditary. A hernia that first appears in an adult dog may have been acquired through injury or strain, which makes it less relevant as a breeding concern.
Small Hernias Often Close on Their Own
Not every umbilical hernia needs surgery. Hernias smaller than about 1 cm (roughly a quarter inch) frequently close without treatment by the time a puppy is 3 to 4 months old. These small, soft bumps at the belly button are common findings during puppy exams, and your vet will typically recommend monitoring rather than immediate intervention.
Umbilical hernias can range from under 1 cm to more than 2.5 cm in diameter. The larger the opening, the less likely it is to resolve spontaneously and the greater the risk that abdominal contents will push through.
When Surgery Is Needed
If a hernia hasn’t closed by the time a puppy is spayed or neutered, surgical repair is typically recommended and can be performed during the same procedure. This is the most common scenario for small-to-moderate hernias: the puppy lives with a harmless little bump for a few months, and then it’s corrected under the same anesthesia used for the spay or neuter.
Larger hernias, or any hernia where intestinal tissue can be felt in the sac, warrant earlier attention. The concern is strangulation, which happens when a loop of intestine pushes through the opening and gets trapped. Blood flow to that section of bowel is cut off, and the situation becomes a surgical emergency. Signs of a strangulated hernia include a swelling that suddenly becomes larger, firm, or warm to the touch, along with vomiting, loss of appetite, abdominal pain, and lethargy. This is uncommon with very small hernias but is a real risk when the defect is wide enough for intestine to pass through.
What This Means for Your Dog
If your puppy has a small umbilical hernia, the outlook is excellent. Most are minor, many close without help, and surgical repair when needed is a routine procedure with quick recovery. The genetic angle matters most if you’re planning to breed. A single puppy with a tiny hernia isn’t alarming, but a pattern of hernias across a litter or a family line signals that the genes driving the trait are being passed along. Selecting breeding pairs with no hernia history on either side is the most effective way to reduce the frequency over time.