Club Foot Heritability

Q: I work on a Thoroughbred farm, and they have a mare there with a club foot. Her mother did not have a club foot, but I am told her sister did and her yearling colt did. I know in the Quarter Horse world, when looking to breed, it is common to breed to a horse that has better conformation than what your horse has. What I would like to know is with carefully resourced breeding could this mare throw a foal without club feet, or is she destined to always pass this on?

A: Club foot is a term commonly used to describe an abnormally upright front foot conformation. It can be a congenital (born this way) or developmental (acquired early in life during foalhood) issue, or it can occur later in life due to chronic lameness or injury that causes the horse to not bear weight fully on the affected limb. In those cases, the underused foot eventually becomes steep and narrow while the healthy foot becomes splayed and flat.

Congenital club foot can range from a mildly upright hoof to one where the dorsal hoof angle (that the front of the hoof makes with the ground) approaches or is beyond vertical. These are commonly termed “flexural deformities” because the deep digital flexor (DDF) tendon and the associated inferior check ligament are abnormally tight in these animals. This creates excessive contraction at the DDF attachment to the bottom of the coffin bone, resulting in downward rotation of the bone. The normal alignment of the short pastern bone and coffin bone is a straight line visible on X ray, but in a club foot the coffin bone angles downward relative to the pastern (a “broken forward” axis).

Source: TheHorse