A recent study to evaluate the likelihood a dog will develop hip dysplasia indicates the standard OFA (Orthopedic Foundation for Animals) scoring method may be missing the mark by a large margin.
The study, conducted by the University of Pennsylvania, involved 439 dogs older than two years, many of which were breeds commonly susceptible to hip dysplasia, including:
- German Shepherds
- Labrador Retrievers
- Golden Retrievers
In a comparison of the traditional OFA and newer PennHIP (Pennsylvania Hip Improvement Program) scoring methods, results showed 80 percent of dogs scored as ‘normal’ by OFA are actually at risk for developing osteoarthritis and hip dysplasia according to their PennHIP ratings.
OFA scores are used to certify dogs for breeding purposes; testing is typically done around the age of two.
The primary differences in the two screening methods involve the positions in which a dog’s hip is x-rayed, and more precise scoring in the case of the PennHIP test. The OFA method uses conventional hip-extended x-rays; the PennHIP method adds a small distraction force, which reveals additional joint laxity of the type that is known to be directly linked to the development of osteoarthritis.
“According to the OFA's Dr. G.G. Keller, director of veterinary services, that assertion misses the mark." (The study) is comparing apples to oranges because the OFA method is not designed to measure joint laxity. They are different methodologies," he says, adding that joint laxity is not the only factor to consider in evaluating susceptibility for developing hip dysplasia.”
The results of the University of Pennsylvania study indicate over half of the dogs’ hips rated ‘excellent,’ 82 percent of those rated ‘good,’ and 94 percent scored ‘fair’ by OFA standards were susceptible to canine hip dysplasia (CHD) according to their PennHIP ratings.
The only area of agreement between the two methods was for dogs with hips OFA scored as ‘dysplastic.’
According to researchers, even if only those dogs with OFA-rated ‘excellent’ hips were bred, from over half to 100 percent of the puppies, depending on breed, would be susceptible to hip dysplasia based on the PennHIP method.
The Penn researchers warn that if breeders continue to breed dogs based on traditional OFA scoring they will continue to mate dogs susceptible to dysplasia, and the hip quality of future generations of dogs will fail to improve.
Dr. Gail Smith, professor of orthopedic surgery and inventor of the PennHIP method, says despite well intentioned hip-screening programs to reduce the frequency of the disease, little progress has been made because CHD is erroneously considered an ‘all or nothing’ disease—the pet either has it or it doesn't.
According to Dr. Smith, the advantage of the PennHIP radiographic method is its ability to determine not only which dogs are immediately susceptible, but which are at risk to develop a problem later in life. "We have to put aside the 'all or nothing' notion. There is a variable degree of susceptibility for the disease," he explains.
Hip dysplasia means ‘badly grown hip.’ Dysplasia comes from the Greek words ‘dys’ meaning bad or abnormal, and ‘plasia’ meaning growth.
What is Hip Dysplasia?
Canine hip dysplasia (CHD, or simply HD) is a polygenetic multi-factorial disease, which means there is a genetic component, more than one gene is involved, and it is caused by a number of factors, some of which have yet to be identified.
Dogs without the genes for the condition will not acquire the disease. Dogs with the genes may or may not develop the disease.
A dog can have great OFA and PennHIP scores and still carry the genes for the disease, meaning future generations of puppies can develop CHD even if prior generations show no signs of it. There is no test to identify whether a dog is a gene carrier.
CHD is said to be present when the ball and socket (acetabulum) hip joint is malformed, causing a ‘subluxation’ or separation of the two bones of the joint. In most cases, the socket is not deep enough for the ball to fit completely into place.
In a dog with healthy hips, the ball (the head of the femur) at the top of the leg bone fits perfectly into the socket. In animals with CHD, the less-than-perfect fit causes the bones to separate. This separation is the result of abnormal joint structure coupled with weak muscles, ligaments and connective tissue that support the joints.
The result is a joint that chafes and grinds rather than slides smoothly during movement. Often the body tries to compensate for the poorly fitting joint by producing hard, bony material in and around it in an attempt to stabilize it. This alteration can have the opposite effect, creating an even more unnatural fit.
Eventually the wear on the joint from the chafing and grinding results in degenerative joint disease (DJD), which causes the dog pain and limits his mobility.
The hip is the biggest joint in your dog’s body and bears the majority of his weight during any kind of movement. That’s why hip dysplasia can be such a painful, debilitating disease, especially as it is predominantly seen in large breed dogs with heavy body mass.
Hip dysplasia also occurs less commonly in smaller breed dogs and in cats.
Symptoms and Diagnosis of Canine Hip Dysplasia
According to PennHIP.org, a dog with CHD may have one or a combination of the following symptoms:
- The disorder develops at 5 months to 12 months for the severe form of the disease; later for the chronic form
- Abnormal gait
- Bunny-hopping when running
- Thigh muscle atrophy (loss of muscle mass)
- Low exercise tolerance
- Reluctance to climb stairs
- Audible "click" when walking
- Increased width between points of the hips
Diagnosis is typically made either because a dog is showing symptoms, or as the result of a standard hip exam prior to breeding a purebred dog.
If your pet is symptomatic, there will be clinical signs of mobility problems and pain. The vet will perform a complete physical exam and take x-rays. Problems with a joint are often easily seen on x-rays of dogs exhibiting symptoms. Your vet may also be able to feel looseness in your dog’s hip joint, and note pain when a rear leg is extended or flexed.
In non-symptomatic dogs, CHD is often diagnosed during the OFA and/or PennHIP certification process intended to establish the health of an animal’s hips.
Traditional Treatment of Hip Dysplasia
Surgery. If hip laxity (looseness) is caught very early prior to any joint damage occurring, there are surgical procedures that can correct the joint malformation.
If your dog has already suffered degenerative joint disease from chronic hip dysplasia, surgical options are either a total hip replacement or a procedure in which the head of the femur is removed and a ‘fake’ hip joint replaces it. This option is less costly than a full hip replacement, but is most successful in dogs weighing less than 40 pounds.
Unfortunately, the cost of surgery for CHD is beyond the budget of many pet owners.
Medical management. Conventional medical management of the condition involves the use of non-steroidal anti-inflammatory drugs (NSAIDs), buffered aspirin and corticosteroids to alleviate inflammation and pain. The side effects of these drugs can include organ problems and gastric ulcers.
If your pet is on medication for the pain and inflammation of CHD, I recommend you work with a holistic vet to determine what alternative treatments might also be of benefit. Often when an integrative approach is taken to managing the condition, safe supplements and therapies can reduce or replace the need for potentially toxic drugs.
In my opinion, the most important aspect of managing this debilitating disease is building and maintaining excellent muscle, tendon and ligament health through physical therapy, an anti-inflammatory diet and oral chondroprotective/supportive supplements.
Complementary therapies include:
- Chiropractic treatments. Chiropractic therapy can help your pet avoid the compensating injuries that often result from CHD.
- Massage. Regular massages can alleviate inflammation and prevent further damage through compensation.
- Stretching and other forms of physical therapy will increase the condition and mobility of her joints, tendons and ligaments, helping to preserve her range of motion.
- Low-level laser therapy can facilitate long lasting pain relief by stimulating the release of your dog’s own pain killing endorphins.
- Acupuncture can be tremendously beneficial in relieving the pain and inflammation of degenerative joint disease.
- Aquatic therapy, also known as hydrotherapy, uses an underwater treadmill or heated pool to take pressure off your dog’s injured or painful joints. Water therapy can also improve your dog’s cardiovascular health, muscle strength and range of motion critical for supporting dysplastic dogs.
- Adding certain supplements to your pet’s naturally anti-inflammatory diet can provide the raw materials for cartilage repair and maintenance, among them:
- Glucosamine sulfate with MSM, Eggshell Membrane, Perna Mussel
- Homeopathic remedies, including Rhus Tox
- Ubiquinol and other antioxidants
- Super green foods (Spirulina and Asthaxanin)
- Natural anti-inflammatory formulas (herbs, proteolytic enzymes and nutraceuticals)
- Adequan injections, which can stimulate joint fluid very rapidly in pets with arthritis
Prevention of Canine Hip Dysplasia
- Selective breeding. More hip testing and more careful breeding can go a long way toward limiting the inheritance of this terrible disease that destroys the lives of millions of wonderful dogs.
If you’re planning to get a purebred large-breed puppy, find breeders who PennHIP certify their dogs. OFA certification is still the established standard, but PennHIP is a much better indication of hip health. If greater numbers of potential dog owners demand PennHIP certification, more breeders will understand the importance of this test for their animals.
Unfortunately, PennHIP testing is more expensive and not as widely done as OFA, but it is highly preferable to the OFA method. The procedure can be done on dogs as young as 16 weeks.
PennHIP uses a network of trained veterinarians and anesthesia is required rather than an option. All tests must be submitted to PennHIP for evaluation, and their database contains every study of both tight and lax hips, giving a more realistic picture of the hip status of each breed.
For maximum impact on limiting the disease, only dogs with a very low PennHIP ‘distortion index’ should be bred, as these dogs have almost no chance of developing the disorder.
Since this option severely limits both breeder choices and genetic diversity, a more realistic approach is to breed only those dogs with hips tighter than the average tightness for the breed. This will move the breed in the direction of tighter hips and less chance of developing CHD, while maintaining other desired traits.
However, it’s important to note no matter how many lines in a dog’s ancestry have good hips, at the present time all we can do is minimize risk of the disease, not extinguish it altogether.
- Slow weight gain in large-breed puppies. When a puppy gains size and weight too quickly, the cartilage in his body often can’t keep up with the growth of his frame, and cartilage deficits result. When imbalances of this type develop in a growing dog, they can contribute to hip dysplasia and osteoarthritis.
High calorie diets, which are typically also high in carbohydrates, can cause too-rapid growth, especially in larger breed dogs.
In fact, research indicates the amount of calories a dog consumes, especially from the age of three to ten months, can have a significant impact on whether a pup genetically prone to hip dysplasia will develop the condition.
Despite what you might hear from other owners of large breed dogs or even from your vet, it is not protein in the diet that is linked to hip dysplasia, but calcium-phosphorus ratios and high caloric content.
In a 1997 study of Labrador Retriever puppies, the dogs fed ‘free choice’ (from an all day, all-you-can-eat-buffet) had a much higher rate of hip dysplasia than their littermates who were fed the same food, but in controlled portions that amounted to 25 percent less than the free fed pups.
The free-fed dogs were also quite a bit heavier as adults than the controlled portions group -- by about 22 pounds on average.
Obesity can increase the severity of dysplasia. Extra weight can accelerate the degeneration of joints. Dogs born with genes that make them prone to hip dysplasia, if allowed to grow overweight, will be at much higher risk of developing the disease, and subsequently, arthritis as well.
- Appropriate exercise. There is evidence over-exercising large breed dogs at a young age may be a risk factor for dysplasia. Activities that require your dog to jump and land can apply a great deal of force to his joints.
However, moderate exercise such as running and especially swimming, will help your pup maintain good muscle mass, which has been shown to decrease the incidence and severity of the disease.
Your pet should get at least 20 minutes of sustained, heart-thumping exercise three times a week. Thirty minutes is better than 20 -- six or seven days a week is better than three.