Club foot is a lack of the attachment of the coffin bone in the hoof that results in varying degrees of malformation of the hoof as well as the stride of the affected horse. Club foot is almost always on one of the front feet, but very rarely on both. About a fifth of the time club foot may be seen on a hind foot, but typically these cases are much less severe.
The coffin bone in the horse's hoof is responsible for giving the exterior hoof its uniform shape, as well as allowing the horse to carry its weight normally distributed throughout movement. The coffin bone is actually in three separate segments, and club foot is noted when the lowest segment, or third phalange, is twisted and out of proper positioning. This is the bone that shapes the hoof and when it is out of alignment with the other two tendons in the foot and leg adjust to try to balance the weight distribution. This adjustment is actually a tightening of the tendons that results in an inward rotation of the toe and a shorter stride. Typically the outside of the hoof will no longer appear smooth and rounded, rather there will also be an indentation or convex appearance to the front of the hoof where the third phalange is no longer pushing outward.
There are many different theories on what causes club foot, but since it is much more prevalent in some lines of Morgans and Thoroughbreds it is likely to be an inherited condition, although it can skip several generations. There are also theories that it can be a problem with tendon development that pulls the bone out of position, damage to ligaments or tendons when the foal is young, calf knees or even a skeletal problem that extends up the leg. Club foot is frustrating in that foals are born normal with no problems, but as they mature the club foot condition becomes obvious. Usually the club foot's hoof will grow much faster than the other feet with the heel being high and boxy, leading to further problems in movement.
Club foot used to be treated by shaving the heel in the belief that this would force the tendon to stretch and relax, thereby re-aligning the foot. There is little research on the effectiveness of this strategy and new research suggests this may make the condition more problematic. Since there are various degrees of club footedness from a slight turning inward of the foot that has no affect on the horse right up to complete lameness in the foot in severe conditions, treatment will vary.
In very severe conditions a surgical procedure known as desotonomy of the inferior check ligament is used to sever the ligament, forcing the tendons to relax and stop rotating the coffin bone. Since this also has implications in affecting the horse's gait this is not routinely done.
Most horses with a club foot will learn to adjust their movement and still make good pleasure horses although they should not be over worked or stressed. These horses should not be used in breeding programs as there is a chance of this condition being passed down to future generations.