Umbilical Hernias in Dogs: More Common Than You Think
The most common hernia in dogs is often overlooked.
Deb Eldredge, DVM |
March 4, 2013
The umbilical cord on this Bichon Frisé puppy is clearly visible. Umbilical hernias, which occur in newborn puppies, are the most commonly seen hernias in dogs. Photo by Isabelle Francais.
Technically a hernia occurs when a tissue or organ pushes through the area designed to hold it. Normally this refers to the body wall, but it can also be the diaphragm (muscle layer that separates the chest from the abdomen).
The most commonly seen hernias in pet dogs are umbilical hernias. These hernias are found on the abdominal wall where the umbilicus is broken off when a puppy is born. The umbilicus may be broken as the puppy emerges, be chewed in two by the dam or cut by the dog breeder.
What to Do if Your Puppies Have Hernias
Normally the body wall seals over this small opening, but sometimes either a small bit of fat escapes through the body wall and remains outside or the body wall does not close completely. Depending on the size of the opening in this second scenario, the dog's intestines may fall out through the opening and become twisted or strangulated.
You may read discussions about delayed closure versus true hernia. Proponents of the delayed closure theory feel that a small bit of fat or omentum (the thin layer of tissue that is like netting around many of the abdominal organs) slips out through the slit in the abdominal wall where the dog's umbilical cord came through before that slit can close up. Once there is tissue in the way, that slit can’t close. These pet dogs have a small bleb at the umbilicus which is not reducible and very often a hole can’t even be palpated in the body wall. Whether these delayed closures are simply a different expression of a hernia gene or a degree in actual hernias is hotly debated among veterinarians and dog breeders.
The classic umbilical hernia has a firm ring of tissue palpable around the "hole” in the body wall. The size of the opening can vary from smaller than the end of your pinkie finger to 2 or 3 inches across. The hernias least likely to cause problems for a puppy are the very small ones which are too small for any intestine to fall into and the ones large enough that intestines can easily slip in and out of. Your veterinarian can evaluate the hernia with you, and you can decide whether it needs to be fixed, to repair it in a young puppy or possibly wait until spaying or neutering the dog to fix it.
The most dangerous hernias are those big enough for a loop of intestine to fall into and that then close up partly or are of a size to begin with that the intestine can’t easily slip back up into the abdomen. Once caught in the hernia, there is potential for the blood supply to be cut off either simply due to not enough room or by twisting of the intestine and its blood vessels.
Surgery to repair a dog's hernia may be as simple as closing up the tissue after removing the band of tough tissue that makes up the ring and replacing any contents into the abdomen. It could also involve the need for a mesh material, often wire, to help support the body wall in the case of a very large hernia.
Hernias and Purebred Dog Showing and Breeding
At this time, the American Kennel Club does allow purebred dogs to be shown who have had an umbilical hernia repaired. Dog breeders and veterinarians again argue back and forth about the dangers of breeding a bitch who has a hernia or who has had a hernia repaired. The argument is that the increased weight pressing down on the area from the pregnant uterus could cause the hernia opening to stretch and enlarge.
Purebred dog breeds known to have at least a predisposition to hernias include representatives of the Toy, Sporting, Terrier, Working, Hound and Herding Groups. It should be noted that an occasional umbilical hernia will show up in a litter and may simply be a fluke. Still, dog breeders should at least be aware of the hernia problem and try to avoid doubling up on this defect.
I can think back to a litter that came in at 7 weeks of age for an examination and a first vaccination. ALL eight puppies had good sized, fairly obvious umbilical hernias. The dog breeder insisted (despite this being a dog breed well known for umbilical hernias) that the bitch must have chewed the cords off too closely. Funny how her first litter of six puppies (with a different stud dog) did not have any hernias!
An informal survey of reproductive veterinarians led to estimates of 90 percent or more of all umbilical hernias in purebred dogs being inherited. One veterinarian also pointed out, from experience, that dog breeders should not overlook hernias in their puppy litters. This veterinarian had seen the development from occasional small, not serious, hernias to full litters with large hernias in one kennel since there was no selection against the trait. Other veterinarians stressed that a small umbilical hernia was very minor compared to other serious genetic defects and that a dog who otherwise was a good candidate for breeding should not be removed from the gene pool just for this.
Certainly any dog breeder whose dog has had an umbilical hernia repaired should notify anyone breeding to their stud dog or getting a puppy from their bitch of the defect. Otherwise, the trait will be perpetuated. At least one dog breed classifies umbilical hernias as a "threshold” trait. This means that there is no simple inheritance of dominant or recessive, but the expression of the defect and the degree of the defect may depend on multiple genes, not a simple one-gene dominant/recessive relationship. Also, it is fair to assume that both the stud dog and brood bitch carry the genetic defect if umbilical hernias show up in puppies.
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