This may be the most important point we make in our series on Canine Hip Dysplasia: Most cases of HD go unrecognised and undiagnosed because people don’t realize it isn’t normal for dogs to become arthritic when they are old. This is worth repeating.
Absent a history of trauma it is not normal for dogs to become arthritic when they are old unless there is an underlying structural problem.
An 8 year old field trial dog that is lame in the rear? Is he written off as having worn out from all the work he has done?
That 12 year old who sometimes has trouble getting up because it hurts, doesn’t want to run much any more, or needs pain meds? Just an arthritic old dog- to be expected?
These two dogs seemed to be fine when they were young. The trial dog probably impressed everyone with his speed and athleticism. To his owners, the 12 year old dog was a perfectly normal hunter and family companion. Nobody knew the dogs were dysplastic because nobody x-rayed them, but the HD was there, brewing up a painful old age for both.
Probably most of us reading this have heard about 6 month old puppies that had such terrible cases of HD they were euthanized (distressingly common in the Ryman-types of the 1980s and 90s). This can happen, but it is not typical. The severity of symptoms and age of their onset is all over the place- anything from a crippled young dog to one that never shows any visible symptoms. However, by far the most common presentation is late middle age to old age arthritis.
We need to point out that we are talking specifically about arthritis that is isolated to the hips. This must be distinguished from soft tissue injuries or spinal/neurological problems that can cause pain and/or weakness in the rear. All older dogs also lose muscle mass, and it is normal for them to become a little stiff, weaker, or slower in old age. What we are referring to is significant, painful arthritis isolated to the hips, which is almost always caused by HD- at whatever age it becomes apparent.
So what is Hip Dysplasia?
“Dysplasia” is a generic medical term that simply means abnormal growth or development. Hip Dysplasia is not ONE thing. “Canine Hip Dysplasia” is a constellation of abnormalities of the hip joint that individually, or in combination, cause arthritic changes in the joint. Those arthritic changes in turn lead to inflammation and pain.
Although the incidence is lower in people, dysplasia in human hips (called “developmental dysplasia of the hips”) is very similar, and causes the osteoarthritis and debilitating pain that often results in hip replacement surgery later in life.
Research into the genes that cause HD is finding associations with many genes that each have a small to moderate effect on how the hip joint develops. They are related to bone growth and ossification of the ball and socket, cartilage development, joint capsule and ligament function, etc.
The main abnormalities that can be seen in an x-ray early in life are subluxation (the ball is not seated deep within the socket), poor fit/congruity of shape of the ball and socket, and/or a shallow socket (acetabula). The arthritic changes show up later. We can illustrate this by looking at a few hip x-rays.
Here is an x-ray of a young dog with normal hips- OFA rated preliminary Excellent. Note how deeply seated the balls are in the sockets, how tight the fit is, and how congruent the shape of the ball and socket are. She is never going to have the arthritic changes caused by HD.
Next is a young dog with Preliminary OFA Good hips. The fit and congruency are not as perfect but the joint is still nice and tight, with well over half of the ball covered by the socket. His final x-ray at 2 years of age looked identical. These are good hips that will not become arthritic from HD.
As a contrast, the following x-ray is a 6 month old dog diagnosed by the OFA as preliminary Mild, with a finding of “subluxation”. Note the little bit of space between the ball and socket. Barely half, or maybe less, of the ball is covered by the socket. There is no detectable arthritis (yet) and this dog is not showing any signs of trouble at this point.
Another Mild, a 1 1/2 year old also with subluxation as the only finding, also showing no signs of trouble.
Here is a 2 year old dog that has been diagnosed by the OFA as Mild, with findings of “subluxation” and “remodeling of the femoral head and neck”. The remodeling represents arthritic changes. The arthritis has barely begun, and she is not showing any signs of pain yet.
Compare the same dog’s left hip from her preliminary evaluation at 22 months of age to what it looks like in the final at 26 months. Obvious changes to the shape of the ball and the bone between it and femur have taken place- early evidence of arthritis.
This next dog was diagnosed in his final OFA as Moderate. At 6 months his hips would have looked like those in the mildly rated preliminary x-rays above, but now there is arthritis. Compare the left and right hips. On the left hip (right side of the film) note the poor seating, and how different the shape of the ball, socket, and femoral neck (the part of the bone that connects the ball to the femur) are compared to those on the right hip. These areas are beginning to show significant arthritic changes.
Once it starts, the arthritis always progresses. Mild often progresses to Moderate, and a very unfortunate dog that rated Moderate or Severe at two years might look like this at age 10 or 12.
One more x-ray to ponder. Some Ryman lines threw hips like this back in the 80s. You could feel, and sometimes even SEE the ball out of the socket just looking at the dog.
Normal hips stay normal. Dysplastic hips develop progressive arthritis that gets worse and worse over the dog’s lifetime. Think of your friend or relative who has had a hip replacement. He/she had no trouble early on. At some point the pain and arthritis began, probably subtly, and it gradually increased in severity over life until it was bad enough to warrant surgery. This is what dysplastic dogs go through.
This condition doesn’t have to happen to so many dogs. Old dogs don’t get gimpy just because they are old. Barring an unusual injury to the joint, normal hips will stay healthy for a lifetime. By working together breeders and owners can ensure that more and more dogs have a normal old age, without the pain of HD. The first step is for everyone to stop accepting old age arthritis as OK, or a normal consequence of ageing, because it’s not.
More information on hip ratings:
RymanSetters.com series on Canine Hip Dysplasia. Our comprehensive guide to HD and the effective steps breeders and buyers can take to control it.
Upcoming Series on Hip Dysplasia
Old Age Arthritis is Not Normal, It Comes From Hip Dysplasia
Chronic Pain From Canine Hip Dysplasia: Can You Miss It?
There Is No Such Thing As “Environmental” Hip Dysplasia