Predicting Colic: Horse Breeds at Higher Risk

From reviewing statistical data from large populations of patients, researchers have noticed that certain breeds of horses are predisposed to certain types of colic.

For example, Elysia Schaefer, DVM, an equine surgery resident at the University of Illinois Veterinary Teaching Hospital in Urbana said strangulating lipomas are common in older Arabians and Quarter Horses. A lipoma is a benign mass of fatty tissue that forms into a circular ball. It is unknown exactly why it starts to grow, or why Arabians and Quarter Horses are predisposed, but it has the ability to cut off blood flow to the intestinal tract.

As the ball of fatty tissue begins to grow, it drops further and further into the abdomen as a result of gravity. The stalk, or piece of tissue that is still attaching the lipoma to the mesentery (a membrane that suspends the intestines in place) can become wrapped around the intestine, causing a painful problem for the horse and an emergency for an equine surgeon. Fortunately, not all lipomas will need surgery. Some might hang out in the horse's abdomen for a lifetime without ever causing signs of colic. However, it should be noted that in a few cases suspected lipomas are identified as malignant versions called liposarcomas that can metastasize to other parts of the body.

Miniature Horses come just a bit smaller, but not necessarily with smaller problems. "Miniature horses are prone to fecolith impaction," said Schaefer. In contrast to the lipoma, which causes pain and loss of blood supply by strangulating the bowel, fecoliths, a hardened fecal ball, can impede the normal flow of food through the intestines. It too causes colic, although in most cases it is not an emergency. Miniatures with this problem typically present with slow, progressive, intermittent abdominal pain.

Standardbred, Tennessee Walking Horse, and Quarter Horse stallions are also predisposed to scrotal hernias. In contrast to the reducible and non-emergency type of scrotal hernia sometimes found in young male foals, where you can manually move the intestines back into the abdominal cavity, "most of the scrotal hernias in adult males are non-reducible and will strangulate the bowel," said Schaefer. In short, these hernias are emergencies. Again, why certain breeds are more prone to this life-threatening problem compared to others is unknown.

On a final note, although anyone who smokes is at an increased risk for lung cancer, it doesn't mean that everyone who takes up the habit will get the disease. The same holds true for horse breeds. If you fall head over hooves for that petite Arabian, don't let the statistics about lipomas sway your vote. Nearly every horse breed has a predisposition to one disease or another, and until equine surgeons can get their crystal ball working, no one knows what the future holds.--Ashley Mitek

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