Canine Hip Dysplasia
Overview
Despite efforts by breeders and the Orthopedic Foundation of America (OFA), the prevalence of canine hip dysplasia is not decreasing. The problem and resulting clinical signs ranges from mild inactivity to severe pain, lameness and immobility. Usually, clinical signs of canine hip dysplasia develop by one year of age but in some dogs the signs become obvious later in life as osteoarthritis gradually worsens. Hip dysplasia is a genetic disorder often beginning in puppies as young as six months of age. Numerous successful treatments for hip dysplasia are available depending on the age and size of the patient and severity of the problem.
Many breeds are susceptible to hip dysplasia, although it tends to be especially common in larger dog breeds including Labrador Retrievers, German Shepherds, Golden Retrievers, Bernese Mountain Dogs, Rottweilers, Saint Bernards, and so on. Mixed breeds are also subject to hip dysplasia. Not even the toy breeds are spared, although frequency is lower in small dogs. Large dog breeds that have a relatively low incidence of hip dysplasia include the Borzoi, Doberman Pinscher, Great Dane, Greyhound and Irish Wolfhound.
Cause of Canine Hip Dysplasia
The primary cause of hip dysplasia is genetic and results in a malformation of the hip joint. During development, the femoral head (ball) fails to fit well into the acetabulum (socket). In very young dogs (6-9 months) the joint is lax and the femoral head slides partially out, and back into the acetabulum. This is known as subluxation.
Over time, the hip joint becomes arthritic because of these anatomical abnormalities. The joint capsule thickens and becomes inflamed, osteophytes (bone spurs) develop, cartilage erodes, the acetabulum begins to fill in with bone. These secondary arthritic changes can develop quickly; puppies with severe hip dysplasia can develop severe osteoarthritis before their first birthday. In cases where the femoral head stays somewhat within the acetabulum, and the dog lives without intervention, the arthritic changes continue to worsen over years. The hip metamorphosis video depicts this chronic gradual deterioration.
Clinical Signs and Diagnosis of Hip Dysplasia
Usually, clinical signs of canine hip dysplasia develop by one year of age, but in some cases the signs become obvious later in life as osteoarthritis gradually worsens. Clinical signs in young dogs (about one year of age) with hip dysplasia can be quite variable. Lack of willingness to play, lying down after short periods of exercise, showing pain when playing or when getting up and down and walking with a stiff gait are common. Occasionally a popping noise, or a palpable “click” are present. Clear-cut lameness may be present but is less common.
Older dogs will often have decreased muscle mass, stand with the rear feet close together (as if walking a tightrope) and be reluctant to go for walks, jump onto the couch or into the car, etc. Crepitus (a grinding feel) can occasionally be felt by placing a hand over the hip(s) while the dog is slowly walking.
Physical examination and hip palpation may aid in the diagnosis of hip dysplasia. However, standard radiographs (X-rays) are needed to confirm the diagnosis. The following images represent radiographs of a dog with normal hips (figure 1) and of a dog with moderate to severe hip dysplasia (figure 2).
PennHIP® radiography has been found to be the best predictor of future hip arthritis development in young dogs. PennHIP® radiography can be performed as early as 4 months of age whereas the traditional X-ray technique for hips is not certifiable until 2 years of age.
PennHIP® radiography can identify young puppies with hip dysplasia that might benefit from early surgical intervention (see JPS discussed below).
Figure 1: Normal Canine Hips
Figure 2: Canine Hip Dysplasia
Treatment Options for Hip Dysplasia
Conservative, Non-surgical Treatment Options:
Treatment options for dogs with hip dysplasia depend on age, size of the patient and severity of the clinical signs. Many dogs with mild hip dysplasia can live with the problem fairly well with conservative management. Weight and pain management are often the key components of conservative management. Pain management usually involves some form of a nonsteroidal anti-inflammatory drug, such as carprofen. Pain medications like gabapentin may also be beneficial. These medicines may be needed either daily or intermittently depending on the severity of the problem. Acupuncture has also been shown to be effective in pain relief.
Glucosamine and other holistic oral products may be helpful in cases of mild hip dysplasia. Such products may result in subtle improved comfort, but they do not repair or rebuild cartilage as some folks suggest. The same is true for similar injectable products (polysulfated glycosominoglycan). Stem cell therapy and platelet rich plasma (PRP) are the latest non-surgical treatment proposed by some veterinarians. Bone marrow or fat derived stem cells may improve comfort for a limited time by mediating inflammation do not repair or rebuild cartilage despite claims by some stem cell companies. Platelet rich plasma is another new regenerative therapy being used for hip dysplasia, and while cartilage repair/regrowth is highly unlikely, recent studies suggest PRP may be an effective tool in the pain management toolbox.
Surgical Treatment Options:
Dogs with moderate to severe clinical signs and anatomical mal-formation are candidates for surgery. In general, 4 surgical options to treat canine hip dysplasia are currently recommended depending on the dog’s age, weight, severity of the disorder and signs clinical signs.
Juvenile Pubic Symphysiodesis (JPS)
is a newer, less invasive procedure involving fusion of the growth plate within the pelvis and is indicated in dogs less than 5 months of age (figure 3). Juvenile Pubic Symphysiodesis alters the pelvic development with the ultimate result of the ball and socket fitting more “tightly,” therefore, decreasing the potential amount of future hip arthritis. Also, compared to other more traditional surgeries for hip dysplasia, JPS is less invasive, less costly, and is an easier recovery. Juvenile Pubic Symphysiodesis should not be thought of as a definitive cure for hip dysplasia, but can significantly improve hip joint conformation and lessen the long-term affects of hip arthritis.
Double Pelvic Osteotomy (DPO)
is appropriate for young dogs under 8-9 nine months of age. Double pelvic osteotomy involves making two osteotomies (bone cuts) in the pelvic bones, reorienting the acetabulum over the femoral head and securing the osteotomy with a bone plate (figure 4).
Numerous factors are considered when deciding which patients will benefit from a DPO. Patient selection criteria must be adhered to for good outcome. Potential patients should be less than eight months of age, have no osteoarthritis, the femoral head should be normal in size and shape and the femoral head should fall into place within the acetabulum on palpation without excessive force or angulations.
Femoral Head Ostectomy (FHO)
is best suited for cats and small dogs (figure 5). Femoral Head Ostectomy involves removal of the femoral head (ball) from the joint. Scar tissue forms between the remaining bone and socket (acetabulum) forming a “false joint”. The primary advantage of the FHO is lower cost, since no implants are needed.
Total Hip Replacement (THR)
is the ideal treatment for medium to large breed dogs with moderate to severe hip dysplasia. Ideally, these patients should be approximately one year of age or older. No upper-end age restrictions exists, but geriatric patients may have a more difficult recovery and higher complication rate.
Figure 3: CT scan showing hip joints before and after JPS surgery
Figure 4: Double pelvic osteotomy
Figure 5: Femoral head osteotomy (FHO)