Thoughts on Hip Testing — Part 2
February 1, 2011 by AKC Gazette Breed Columnist • Categories: Breed Columns
In the November issue (Part 1), I spoke with Deb Lang and profiled her Norwich Norma, who suffers from severe hip dysplasia. I also looked at the basics of hip testing, describing the terminology and the two popular rating systems—that of the Orthopedic Foundation for Animals, and of PennHIP (the University of Pennsylvania’s Hip Improvement Program).
The OFA system is basically a qualitative measure. One X-ray is taken, and grades are assigned according to the judgment of three board-certified veterinary radiologists. To date, Norma is the only NT entered in the OFA database classified as Severe.
A PennHIP rating requires three X-rays: (1) the standard hip-extended view, as used by OFA; (2) a compression view, which evaluates how well the femoral head fits into the socket; and (3) a distraction view; taken while the femur head is pulled away from the socket. A quantitative measure (distraction index or DI) determining hip-joint laxity is then assigned. The closer the measurement is to zero, the tighter the hips; the closer to 1, the looser the hips.
In 1984, when Mary Lou Retton captured the Olympic gold medal in the all-around gymnastics competition at the age of 16, she was a vision of grace and agility. “I had more mobility and rotation in my hips than most,” she remembers. So it came as a complete surprise when she found out 20 years later that she had hip dysplasia. It was a condition she was born with, the degeneration no doubt exacerbated by the stresses of her gymnastics career. Her incredible flexibility is called hypermobility, an advantage shared by many who gravitate to fields such as ballet and gymnastics.
In dog parlance, these athletes have loose hips, or hip-joint laxity. Is our breed prone to this condition? Certainly we have all noticed the charming way they can lie with both rear legs extended straight out behind them. “Like a pelt,” I’ve aways said of this look. Or how about the common Norwich “sit,” with one leg extended out tot he side? Both are ubiquitous in our breed.
Designed to be ratters, the Norwich’s job has been to get into tight spots—something that hypermobility might facilitate. They seem to be almost double jointed in this regard. They were not bred to chase game or retrieve. They didn’t need to have tight hips to do their job. The standards in place today were put there to help dogs with a completely different set of athletic demands. That is not to say that we shouldn’t be breeding Norwich that are fit in every sense of the word. Lang and many breeders are adamant about breeding away from HD. But how realistic are we being, and how good are the measuring systems we have in place?
Veterinary scientists are at odds over theses questions, and it doesn’t look like the controversies over varying methods are going to be settled any time soon.
In the next column (Part 3), I will look at Norwich hip-health according to the OFA and PennHIP databases and discuss some of the pluses and minuses of both systems.
— Leandra Little, AKC Gazette Breed Columnist · Weehawken NJ · llittle9@earthlink.net