A six-year-old event horse hasn’t been right behind for a while. He’s been looked at by vets, farriers and trainers to no avail. His hocks and stifles have been injected. No help.
His impulsion is poor, although he’s more unwilling than weak. He’s stiff, sometimes hesitating midstride behind. He’ll even sometimes tense up his hindquarters.
It’s not tying-up, as his blood work is normal. He’s worse after a hard work and can take days to come out of it. He doesn’t warm out of his stiffness either, like a horse with hock problems will.
Finally, someone mentions his hunter’s bump. Huh' You’ve seen horses with a hunter’s bump and thought nothing of it. Think again.
“Hunter’s bump” refers to a horse that appears to have one hip higher than the other when viewed from behind, looking at the highest point of his croup. Some people incorrectly think it’s the higher side that is normal and call it a “dropped hip.” A true dropped hip can occur if the horse is hit with great force and fractures his pelvis, which then tips down out of place. However, this would cause a tremendous amount of pain.
It’s more likely that the abnormality is on the side that looks higher. The problem is a dislocation of the sacroiliac joint with ligament tearing, swelling and eventual scarring.
The sacroiliac is the connection between the sacral spine and the pelvis at the ilium. When a horse gallops or pushes off for a jump, and has one hind leg far forward under his body, his weight comes down and back, which makes his sacrum go counterclockwise while his ileum goes clockwise (see Dr. James Rooney’s ”The Lame Horse”). If the forces are great enough, tearing and dislocation occurs.
The diagnosis is often missed if the swelling doesn’t cause a bump and people don’t look for it. If you put firm pressure over the sacroiliac joint in a horse with problems here, you will get a reaction that leaves little doubt as to diagnosis.
To find the spot, use your own back first to visualize it. The small of your back is the same as where the rump begins and flank ends in the horse. If you move a few inches below your waist and off the midline an inch or two you will feel two distinct dips or notches. You can’t feel these dips on the horse because of overlying muscle, but his sacroiliac joint lies in an equivalent location. You may have to search in this area, 1?? to 2 inches off the midline and a few inches back from the end of the flank, but if the sacroiliac area is tender the spot will be distinct and more sensitive.
Although rarely done, a rectal examination can diagnose sacroiliac- joint and other problems in the hips and pelvis, even spine tenderness.
There’s no specific treatment for a hunter’s bump. Many are permanent elevations but become painless and the horse goes back to work with no problem. The best approach is to turn the horse out in a large field for six to 12 months. The constant movement will help ensure he retains full function of the leg.