One canine disease most folks are familiar with is dysplasia. It’s a nasty disease that wears away the joint and eventually causes pain, reduced mobility and can lead to major surgery.
It is not easy to pin down the causes of canine hip dysphasia. Genetics, diet, environment, activity level all play a part. And sometimes even when both parents have great hip joints, a pup can develop it.
While getting tests on ALL pups would be ideal in order to get the best picture possible of the inheritability of hip dysplasia, the cost and ability to get new owners to agree to this is daunting. So most reputable breeders rely on testing the only the parents.
There are a few ways to evaluate canine hip dysplasia all which require an X-ray.
1) Have your vet complete an xray and give you an opinion on whether there is any dysplasia evident. I imagine most all vets would give their honest opinion, good bad or indifferent, but if they aren’t a board certified orthopedic vet, their opinion would carry less weight. I don’t know any reputable breeders using this method.
2) Have your vet send the film to the OFA (Orthopedic Foundation for Animals) where for an additional fee, 3 orthopedic vets will do an evalution and give it a rating of Excellent, Good, Fair, Borderline, Mild, Moderate, Severe.
Inter-rater reliability of the orthopedic vets has been sited at about 95%, which is pretty darn good. Generally, what is being evaluated in the xray is how well the ball and socket fit together and if there is any wearing away of the bone or other bony abnormalities.
Anything less than Fair is generally considered unacceptable for breeding.
Most reputable breeders use OFA for screening to determine if there is dysplasia. A preliminary test can be done before two years of age, but a final evaluation should be done after the pup reaches two.
More interesting to me was looking at a graph for Shetland Sheepdogs' OFA scores over the course of several years. There was essentially no substantial increase in the number of “Excellent” scores over the course of decades.
This says to me that we were not doing anything helpful with this xray. And while it might feel good to get an “Excellent” rating for your Shetland Sheepdog, if it won't help you choose the right specimen to breed for improvement in the future generations, what’s the point?
But there is another choice
I prefer to use the PennHip xray method for evaluations rather than the Orthopedic Foundation for Animals x-ray.
I prefer to use this method of evaluating hips. Developed at the University of Pennsylvania in 1983, it was a newer way to measure the probability of dysplasia more accurately. Not only is the fit of ball and socket evaluated, but the laxity of the joint (how far the hip joint could be stretched away from the socket).
The greater the ability to stretch, the greater the chance the joint could wear down improperly and cause canine hip dysplasia (CHD).
It requires that the pup is anesthetized (not my favorite thing to have to do to my Shetland Sheepdogs but ya gotta do, what ya gotta do) and the X-rays performed by a veterinarian certified by PennHip.
The X-rays are then sent to the PennHip folks to be read and there are two measurements: a percentile rating for the individual pup compared to others of his breed, as well as an objective number for the laxity of each joint.
The greater the amount of laxity in the joint, the greater the chance the dog will develop canine hip dysplasia. So this test helps in determining if a dog with good hips may eventually go bad in the future.
In addition to these two criteria, the hips are also reviewed for current hip dysplasia.
This is the test I prefer to use. Why? ‘Cause I love throwing tons of money away? (Lots more expensive than OFA, BTW).
Because I think I get better information from this type of test in spite of the low number of Sheltie breeders using it. (I swear the number of Shelties in the data base only goes up when I submit a test.)
When dealing with canine hip dysplasia, I consider the 50th percentile as the lowest acceptable rating for my breeding stock. With subsequent generations, where both parents have been tested, improvement in distraction index is the litmus test.
The thing with any test is, you don’t want to throw the baby out with the bathwater. If, for example, a lot of Shelties have loose hips and you take ALL of those out of the gene pool, there won’t be anything left to breed. It would be the proverbial genetic bottleneck.
Nevertheless, culling the poor specimens is necessary. ‘Tis a hard pill to swallow to see an otherwise a lovely bitch who doesn't make the grade. Been there, done that.
Think about what it’s like to choose a dog, raise her, spend $600 on a hip X-ray just so you turn around and sell her as a pet because her hips aren’t good enough. UGH!
People tend to think breeding dogs is easy until they see the cost involved to do it right and the tough choices that need to be made when testing reveals a problem. But if those tough choices weren't made, the result could be someone stuck with a puppy that quickly turns into a debilitated mess.
The other point to keep in mind is, you can't cull if you don't know where the problems lie. And with the traditional OFA (Orthopedic Foundation for Animals) hip dysplasia Xrays there hasn't been the betterment of the hips in decades, so that is simply throwing good money after bad.
But, you say, evaluating canine hip dysplasia is as easy as looking to see it running and jumping effortlessly. He has to have good hips, right? Why X-ray at all?
I had an English Shepherd bitch evaluated using PennHip when she was 1 ½ yrs old. She could fly over farm gates and run like the wind. She could go all day long. And she already had evidence of hip dysplasia on the films.
No way would I breed her. I sent her back to the breeder from whence she came. And he promptly bred her. Can't cure stupid...
Finally, I like PennHip better when dealing with canine hip dysplasia because the X-rays can be reliably done as early as 16 weeks old. I prefer to wait until older, but there is no guesswork as to the soundness of hips before they are used for breeding.