Umbilical Hernia - Genetic Unsoundness?

One of today's callers had bought a weanling colt sight unseen over the Internet and when it arrived, the buyer discovered that the colt still had sutures from an umbilical hernia repair surgery. The caller's vet had advised her that an umbilical hernia was considered an heritable "unsoundness" and therefore that the colt should be gelded. The caller had purchased the colt as a stallion prospect, so of course the vet's opinion was bad news indeed.

I've known a fair number of weanlings with umbilical hernias and had not previously heard it characterized as a genetic unsoundness, so I pulled out my trusty copy of Horse Owner's Veterinary Handbook by Drs. Giffin and Gore. Here's what it says:

These hernias occur in both sexes. Ligation of the umbilical cord, manual breaking of the cord, and cord infection with abscess are predisposing causes. Most umbilical hernias close spontaneously by the time the colt or filly is a year of age.

Hmm, no mention of an umbilical hernia being hereditary or an unsoundness.

I checked my backup veterinary reference, All Horse Systems Go by Dr. Loving. Dr. Loving states that:

At birth a foal may have a defect in the abdominal wall along the midline of the belly around the umbilical stump, referred to as an umbilical hernia. A one-to-two-finger-wide opening does not usually pose a problem, and many of these resolve as the foal grows. However, if the defect is more than two fingers wide, it is large enough for a loop of small intestine to slide into the hernial sac. By gently pushing on the swelling with a finger, you can usually push the bowel out of the hernia back into the abdomen. However, entrapment (incarceration) of a loop of bowel in the hernia creates the potential for the intestinal piece to lose its blood supply and strangulate. Such an event can be sudden in onset, accompanied by severe signs of colic pain. An umbilical hernia is easily corrected with surgery to prevent an acute crisis.

So, it appears that a second veterinary reference fails to state that a hernia is an unsoundness or genetic. I did a quick search on Google for "unsoundness equine umbilical hernia" and turned up some anecdotal evidence that some horsemen consider an umbilical hernia to be an unsoundness. Intrigued, I went to my small library of vintage horse books.

Granted, my selection of vintage veterinary books consists of just a few volumes. However, none of them mentioned umbilical hernias at all. They did, however, contain an interesting laundry list of unsoundnesses, many of which are hardly ever heard of today (thankfully!), such as fistulous withers, poll evil and sweeney. If you are interested in the history of horsekeeping and other animal husbandry, I highly recommend The Successful Stockman and Manual of Husbandry by Andrew A. Gardenier (copyright 1899).