Dropped Hip/Hunter's Bump

My horse has an "uneven" hip that has been called a "hunter's bump" or a "dropped hip" by various people. Can you please tell me what these are, and how they are different?

There is not another group on the planet that has the specialized vocabulary of horsemen; but a "dropped hip" in reference to a horse is a new one on me. It is not recognized terminology in equine veterinary medicine or in horseman's jargon. Your companion might be referring to a condition horsemen know as "hunter's bump." Or she might have noticed that your horse appeared lame on a rear limb and exhibited a corresponding "drop" in the affected hip at the walk or trot.

When your veterinarian examines a horse for a suspected hindlimb lameness, he will pay particular attention to the horse's movement as viewed from behind. For example, a horse with pain in the left rear leg will bear less of his weight on the left limb, spend less time with the left limb on the ground, and might not flex or extend the joints as far as the normal hindlimb.

Those three abnormalities are visualized as a difference in the way the gluteal (rump) musculature contracts and relaxes at a walk or trot. A sound horse's musculature appears perfectly symmetrical as he moves forward in a straight line. A horse with a left hindlimb lameness might not fully contract the gluteal muscles during the weight-bearing phase of his gait, making the left gluteals appear lower than the right. He might get off the left rear much faster than the right. This also produces a limp or "dropped" appearance in the left gluteal muscles as he quickly shifts his weight to the right rear limb. Imagine yourself with a limp; you bear as little weight as possible on the sore left leg and quickly shift your weight to absorb the added concussion as your left hip "drops." The principle is the same in the horse. If your horse is lame, your companion might have been astute enough to notice the asymmetry, although her terminology was unfamiliar.

She might have been calling your attention to a hunter's bump. The medical term is sacrcoiliac subluxation. Simply described, it is a tearing of the fibrous attachment that holds the pelvis and the spine together. Once this attachment is loosened, the pelvis actually shifts out of place (see illustration) causing a characteristic bump visible on the horse's rump. This injury is most common in jumping horses, trotters, carriage horses, and some endurance horses. It usually is a result of repeated trauma rather than a single discreet accident. However, a twisting fall or slip can also cause the problem.

The bump that appears is actually the bony prominence on the top of the pelvis made more visible due to its displacement or subluxation. In the acute (early) stages of the condition, the bump might not yet be visible. The only complaint could be that the horse is stiff in the hindquarters. Jumpers refuse to jump or jump poorly. The horse might have a shortened stride on one hindlimb if only one side of the pelvis is affected.

Stall confinement, ice application, and anti-inflammatory drug therapy is the accepted and safest method of treatment. Some feel that alternative therapeutic modalities such as acupuncture or ultrasound can provide beneficial effects in healing. The torn ligament needs time to heal and scar to allow maximum reattachment and stability. If work is continued, further damage to the ligament can occur and pain and inflammation will persist.

When the condition is noticed and diagnosed early, the prognosis is favorable. With repeated injury or extensive tearing of the ligament, permanent lameness might result.

If your horse has the classic "hunter's bump" appearance, but is not currently in pain, it is likely that the subluxation occurred some time ago and has healed sufficiently to reestablish a solid connection between the pelvis and sacral spine. However, even a well-healed injury in this area is more likely to recur than in a normal pelvis. Owners should be aware of the risk and take precautions whenever possible; i.e., thorough warm-up and cool-down, avoiding slippery footing, and most importantly, know your horse's physique and behavior patterns. The sooner you know something is amiss, the sooner your veterinarian can make an accurate diagnosis and prescribe appropriate therapy.

About the Author

Mary DeLorey, DVM

Mary S. DeLorey, DVM earned her veterinary degree from University of Missouri in 1992. Since 2000, she has devoted her entire professional energies to equine dentistry. Her practice, Northwest Equine Dentistry, Inc. serves the states of Washington and Idaho and is based near Seattle. Dr. DeLorey has traveled internationally to instruct veterinarians in equine dentistry techniques and speaks to horse owners nationwide. She trail rides and raises sport ponies from her ranch in Eastern Washington when she's not on the road.

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