Hip dysplasia in puppies is a progressive, degenerative disease of the hip joints, and is the most common cause of rear-end lameness in dogs. Canine hip dysplasia is most often seen in large breeds like German Shepherd Dogs, Saint Bernards, and Greater Swiss Mountain Dogs, but any size dog may be affected and both male and female dogs are affected with equal frequency.
The cause of canine hip dysplasia isn't known. The condition is thought to have a genetic link, and dogs suffering from hip dysplasia should not be bred. Puppies from parents that have hip dysplasia will be two times more likely to develop the disease as puppies born to parents with normal hips. However, even dogs with normal parents can develop hip dysplasia.
What Is Canine Hip Dysplasia?
The pelvis cradles the head of the femur (thigh bone) in a cup-like socket of bone that forms the hip. Puppies typically are born normal, but as the puppy matures, the hip joint alignment becomes progressively worse.
As a young pet grows, if the alignment isn’t just right due to bone abnormalities or laxity of the ligaments and muscles that hold the joint together, the misalignment causes wear and tear on the joint. Pups suffering from dysplasia typically have a very shallow socket and/or loose muscles and tendons. This allows the joint to work loose, which places abnormal stress and wear on the bones when they rub together and causes further joint degeneration and pain. Bones respond to stress by growing thicker, which makes the fit even worse. As the dog matures, this damage predisposes to arthritic changes and painful joints.
Signs of Hip Dysplasia
Severe hip dysplasia may become noticeable as early as four months of age, but more typically is seen in the nine to twelve-month-old pup. The painful condition causes limping and favoring of limbs, difficulty rising, running or jumping. Dysplastic pups may exhibit an odd wavery gait when walking, and "bunny hop" when running which helps minimize joint stress. Stairs can prove a challenge to these dogs, and sore hips may prompt aggression causing the pup to snap or flinch when touched.
However, there are degrees of severity. Some pups may show few to no signs at all and mild cases may go undiagnosed until the dog reaches middle age or older. How quickly or to what extent degeneration occurs is in part determined by the pup's activity level. While healthy, normal hips probably won't be adversely affected by hard work or exuberant play, the dog with mild to moderate hip dysplasia develops more severe signs more quickly when excessive stress is placed on these joints. Fortunately only a relatively small percentage of pets suffer the severest, crippling form of the disease.
Genetics accounts for about 25 percent of a pup’s chance of developing hip dysplasia, and even dogs with normal parents can develop the condition. Hip dysplasia is considered “poly-genetic” by veterinarians which means the genetic component of the disease can be influenced by lifestyle, nutrition, weight, and activity level.
How Is Hip Dysplasia Diagnosed?
Outward signs may point to a problem, but for a conclusive diagnosis, X-rays are performed while the puppy is under anesthesia. The puppy is placed on his back and the veterinarian looks for the typical arthritic changes and subluxation (laxness) of the bone fit. Some changes may not be evident until the pup reaches two years old, and experts say there can be great changes from six to nine months to a year.
That’s why OFA certification cannot be done prior to age two in dogs. The Orthopedic Foundation for Animals (OFA) provides a consulting service for purebred dog owners and breeders. OFA reviews hip X-rays provided by an owner to evaluate the dog's conformation and, when normal, certifies that fact.
The PennHip testing method, developed by Dr. Gail Smith, a veterinary orthopedic specialist at the University of Pennsylvania, also positions the pet on his back, but then fits a metal and acrylic form, called a “distracter,” between the animal’s hips. This brace positions the pup’s rear legs sort of like a frog pose, to replicate what happens when standing. The resulting X-ray helps gauge the pet’s laxity score or “distraction index” and allows veterinarians to determine the degree of joint looseness even before bone changes from damage occur. Whatever laxity or looseness they have at four months, they’ll have for the rest of their life.
Reputable breeders have dog parents tested prior to breeding to make sure they do not have hip dysplasia and reduce the chance of the condition in puppies. Dogs can be certified free of hip dysplasia by sending appropriate X-rays to either the OFA registry or the PennHip registry. OFA costs less because there’s only one X-ray taken. This is evaluated by three radiologists who score the hips fair, good or excellent. PennHip evaluation uses computer analysis to compare the X-rays to all the other dogs of that breed in the registry.
Management of Hip Dysplasia
There is no cure for hip dysplasia. Treatment is aimed at relieving pain and improving joint function. How well treatment works depends on the severity of the problem.
Often, mild to moderate cases of hip dysplasia can be managed with gentle exercise, a healthy diet, and oral pain relievers like buffered aspirin or Rimadyl as prescribed by the veterinarian. Moderate exercise helps maintain and improve the puppy's muscle tone, which alleviates painful wear and tear on the joint.
Encourage your dysplastic puppy to take short walks with you. Swimming is ideal exercise, but jumping and prolonged running should be discouraged. Keep him lean; obesity increases joint strain and can make the condition worse. Massage can also help him feel better.
Severe cases of hip dysplasia may benefit from surgery that rebuilds or removes bone or alters the muscles and tendons to reduce pain. Such procedures may not fully restore joint function but can give the dog improved movement and improve the pup’s long-term quality of life.