Doc,
We were practicing at a friend’s house last night and during our third run there was a real loud popping sound just as he set the steer and the horse could not even put his left hind leg down. He would try to swing the leg forward but not even try to bend it or put any weight on it. There were several of us there and he is pretty gentle so we helped get him into a trailer and we took him to the vet. It was pretty late when we got him there and the main vet was gone but one of his young assistants treated him and they were going to look at him a little better this morning. I know you haven’t seen him but what do you think might have happened?
You are right... it would be impossible to do anything but guess, as I was not there, but I have seen several horses injured in a similar fashion over the years, so we will discuss some of the possibilities. I will say this, in every case like this that I can think of, the history was the same but each horse had sustained a different injury.
It sounds like he might have fractured his pelvis or his hip. Figure 1 shows the skeletal structure of the hind quarters with the pelvis, the femur, and the hip joint labeled. Figure 2 shows the pelvis as viewed from the front with the pelvis, the sacrum, and the hip joint labeled. While the femur joins the pelvis at the hip joint it is not shown on page 41 in Figure 2.
Fig. 1
We really don’t have any practical way to measure the forces that these team roping horses exert on the different parts of the body during a typical run. All of us that rope have experienced the forces that they exert so it is easy to understand how some of these catastrophic fractures occur. I have seen a few of these injuries occur when it appeared that the run was a nice smooth controlled run and I have seen some occur when there was a wreck of some kind. Frankly the wrecks are easier to understand.
The heading horse usually exerts more strain and pressure on the hindquarters during a run than does a heeling horse. Injuries can occur as they break from the box, begin to set the steer, drop the shoulder and hind end to begin to roll the steer out of the hole, exert the effort to pull the steer across the arena, or as they face at the end of the run.
A pelvic fracture can occur anywhere in the pelvis but, in a team roping horse, it usually occurs from the mid pelvis downward to the hip area. In Figure 1 the line drawn from the word “Pelvis” to the skeleton points to the ilium of the pelvis and this is a very common area for this type of fracture to occur. The areas of the pelvis that are adjacent to the hip joints (and even including the hip joints) are also a very common location for these fractures.
In Figure 2 (below) the line drawn from the word “Hip” to the femur points to the head of the femur and a fracture of the neck of the femur that connects the head of the femur to the body of the femur can also occur. I don’t recall ever seeing a fracture of the neck of the femur in a horse that hadn’t been involved in a fall of some kind however. Any of these fractures of the pelvis or femur may show the clinical signs that your friend’s horse showed as they typically will not bear any weight on the leg and will try to advance the leg by swinging it rather than flexing the hock and stifle.
Fig. 2
We have discussed some of the lower leg fractures (such as a fracture of the second phalanx) that can occur as you have described, but those horses can readily flex the hock, stifle, and hip but are unable to bear weight on the leg. You can very often hear the fracture occur in the lower leg just as you heard in this horse.
Many of the pelvic fractures can be diagnosed by your veterinarian by rectal examination allowing him/her to actually palpate the fracture of the pelvis. That is especially true of the ilium of the pelvis and the areas of the pelvis along the bottom of the bone and near the hip joint.
The hindquarters of our team roping horses are so massive that it is almost impossible to radiograph the pelvis in a standing horse. Most veterinarians are very reluctant to anesthetize a horse for radiographs because during the recovery there is a very probability that it would further injure itself and make matters worse.
The treatment of these fractures depends on the location of the fracture and the amount of displacement of the fracture fragments. Sometimes resting the horse for a year will allow some of the fractures to heal and yield a sound horse. Others will never heal. If the fracture involves the hip joint then the prognosis is much worse.