Another way to modify expression of canine hip dysplasia is exercise modification and physical therapy. There are many people
now trained in ways of modifying the physical activity of dogs to help them function better. It goes along with diet and the
most important treatment of all-body weight reduction to an ideal body weight.
A surgical option for dogs less than 4 months old is a juvenile pubic symphysiodesis, which fuses the bottom of the pelvis
and stops it from growing. The top part of the pelvis grows and, hopefully, eventually captures the femoral head. But that
When the dog is a little older, say 4 to 6 months, you can do a triple pelvic osteotomy, which physically repositions the
cup over the femoral head. You're not going to have a perfect hip, and the dog will still get some degree of arthritis down
the road, but the idea is to make it better than it was before.
Surgery at maturity would be either a total hip replacement or an excision arthroplasty, where you remove the femoral head
and neck, and a false joint forms. This works very well in small- to medium-size dogs. It also gets rid of pain in larger
dogs, but the physical and mechanical function is not as good as a total hip replacement. Total hip replacement works very
well if done by people who are good at it. Like all types of total joint replacements, the big issues are infection, fractures,
loosening, luxations, and nerve damage, some of which can occur immediately after the surgery or at some point down the road
just like they do in human joint replacements.
DVM: Please discuss your own research, the dorsal lateral subluxation imaging test and the genetic mapping project on dogs with
hip dysplasia. How do you see your work impacting the care and treatment of affected animals in the future?
Todhunter: We developed an imaging method where the dogs are positioned in sternal recumbancy—on their chest and kneeling on their stifles—mimicing
what you would do in the initial phases of the Ortolani test. We take a dorsoventral image, in what we believe to be a more
functionally relevant hip-imaging position.
What we've shown is that this type of imaging is more accurate in determining whether the hips will eventually become arthritic.
The sensitivity is around 80 to 85 percent, and if you add a second imaging position like the OFA view and measure the Norberg
angle, you can improve the accuracy of the arthritis prediction.
At the moment we are undertaking genome-wide genetic marker screening tests on populations of dogs to identify which genes
contribute to the affected phenotype. Eventually we want to get enough genetic markers and enough animals that have been phenotyped
so we can narrow our investigation to the affected region and start to look at candidate genes.
I've been pushing the idea to combine genetic information contained within a dog's pedigree with the phenotypes and the hip
confirmation information (together called a breeding value) and provide it to breeders or potential purchasers of puppies.
The pedigree information improves the estimate of the dog's genotype, and when you combine that with the radiographic information,
you get a much better idea of the likelihood of a good or bad outcome.
DVM: What would you like general practitioners to know about this disease?
Todhunter: Prevention is better than cure. Once established, you can't cure the hip problem except by removing it. So let's focus on
the available tools to try to breed dogs with better hip conformation. In fairly short order we'll be able to supply breeding
values that will provide owners with even better tools for breeding and purchasing selection.
Once you have a puppy, you need to restrict its growth and check it when it's being vaccinated. At maturity, screen it for
hip quality using two of the radiographic assessment tools easily available.
Eventually, veterinarians should be on the lookout for genetic marker-assisted selection, which will use molecular genetic
tools to identify dogs that are susceptible and resistant to hip dysplasia.
I predict that when the public knows these tools are available, they're going to demand them, so veterinarians have to be
ready to answer questions, provide tests, and then know how to advise breeders and owners appropriately. We're just at the
uptick of this slope, and in the next five to 10 years you're going to see many of these developmental problems starting to
be resolved and the underlying genetics understood.
Wetzel is a free-lance writer in Cleveland, Ohio. For more information, visit the Orthopedic Foundation for Animals website,