Monday, May 23, 2011

CONFORMATION FAULT: Sickle Hocks

For this installment of our new series on conformation faults, we spoke to Charles Hutton, PhD, an instructor in breeding management at Murray State University in Kentucky, and owner of Nu Chex To Cash, an NRHA Million Dollar Sire, Multiple World Champion and World Champion Sire. Dr. Hutton has a particular interest in applied equine genetics and conformation.

            Small hock angles, also known as sickle hocks, is a conformation fault in which the point of the hock lines up under the buttock correctly, but the canon bone angles forward so that the horse is standing under from the hock down. In profile, the leg appears to curve forward, giving it some resemblance to a sickle. This conformation places the plantar (rear) aspect of the hock under great stress, predisposing the horse to sprain and strain of the soft tissue structures that support the back part of the hock. Most experts agree that any horse with hock angles of less than 53 degrees is sickle-hocked.

On the left, we see a good hock angle. On the right, the horse is sickle-hocked.


At one time, it was thought that sickle-hocked horses had some advantages in Western performance sports. As conformation expert Dr. Charles Hutton of Murray State University recalls, “There was a time when people, including some judges, would say that they wanted a horse whose hocks ‘set up under him’ because it made it easier for him to stop. To a limited degree, that’s true, because when you’re starting a sickle-hocked horse in training, they often do seem to have an advantage stopping. But the problem is that they get sore, and once they get sore, they quit.

“Horses with this problem are often not clinically lame – they just can’t  perform all that well because it’s uncomfortable for them. Some of them do become clinically lame with what’s called a curb, which is an inflammation in the ligament of the accessory metatarsal bone on the rear of the hock. But typically, unless they’re worked real hard, they just have performance weaknesses because of soreness. Fortunately, we don’t see nearly as many horses with this conformation fault in the reining world as we used to.”

Still, there are sickle-hocked horses out there, and if you have one, it is important to learn what you can do to help keep your horse sound and comfortable. In general, horses with severe sickle hocks should not be subjected to intensive training and competition, but if the problem is mild, you may still be able to aim high if you are careful. Explains Dr. Hutton, “If a horse is only a little bit sickle-hocked but I felt that it was a horse that was otherwise going to make it, I would ride that horse a bit differently. By that I mean that I would put less pressure on its hocks in training and slow down my progression of exercises that lead to the big stop.

“It is also very important to work with a farrier who understands that your horse has this weakness, and who would be particularly careful to keep the hoof angle in agreement with the pastern angle. I wouldn’t exaggerate it by standing the horse up, but the toes must not be allowed to become long. If you let a sickle-hocked horse get long toed in the back, you’re going to exaggerate the stresses that the sickle hock already creates.”

As for breeding a horse with sickle hocks, Dr. Hutton says, “If a horse is an otherwise outstanding horse, I would not necessarily say you should cull it from the breeding program, but in general, such horses are not top performers. Still, I’ve seen mares who were a bit sickle-hocked bred to a stallion that corrected their fault and they got real good results. Personally, I can tell you that over the years we’ve been selecting and culling our mares, and we no longer own any sickle-hocked mares. I do have a daughter out of a Smart Little Lena mare we used have who was moderately sickle-hocked. I sold the mare, but that daughter is by Nu Chex to Cash, who sires really good hocks, and it looks like she might be one of our best three year olds. It’s true of many faults that if you breed in a very discretionary way and really study the stallion you’re considering breeding to and his offspring, you can find a horse that specifically improves a particular weakness.”