Canine Hip Dysplasia (CHD)

Canine Hip Dysplasia (CHD) is a developmental condition of the hip joints. Any breed can develop this condition; however, large breeds are the most commonly affected. Male and female dogs are affected with equal frequency. It is one of the most common skeletal diseases seen by veterinarians although the actual incidence of canine hip dysplasia is unknown. Hip dysplasia is a disorder of the hip that begins with joint laxity and progresses to arthritis over a period of several months to years. While there is a genetic component to canine hip dysplasia, many other factors influence its development, including the body type, size, growth rate, and nutrition of the dog. Overfeeding, in particular, dietary supplementation for maximum growth has been shown to increase the incidence of hip dysplasia in young, growing, large breed dogs.

The American Veterinary Medical Association’s (AVMA) American Board of Veterinary Specialties (ABVS) is the umbrella organization for veterinary specialties in the United States. There are currently 22 AVMA-recognized veterinary specialty organizations. Dogs suspected of having canine hip dysplasia should be seen by a board-certified surgeon as soon as possible.

Additional Details and Symptoms

Whenever your pet is showing signs of a health issue your first step is to contact your primary care veterinarian. If it is indicated that your pet may suffer from Canine Hip Dysplasia (CHD) or another serious condition, a veterinary specialist is available at an ExpertVet certified hospital.

The hip is a "ball and socket" type of joint. In the normal dog, the head of the femur, the "ball" portion, sits tightly into the acetabulum of the pelvis, the "socket" portion. In dogs with hip dysplasia, there is a developmental abnormality with this ball and socket joint; the dog develops loose and abnormally shaped hip joints as it grows. This abnormality is known as incongruency between the shape and function of the femoral head and the acetabulum. The angle of the top of the acetabulum may not be level, allowing the femoral head to slide in and out as the dog walks; damage to the cartilage and joint lining occurs with every step. The end result is progressive abnormal development of the acetabulum and extreme pain for the dog. Although hip dysplasia is genetically inherited, overfeeding of high protein/high calorie diets and over-supplementing with vitamins or minerals, especially calcium, can worsen or accelerate hip dysplasia development in fast growing puppies.

Symptoms of canine hip dysplasia are commonly noted between the ages of five to eight months, with some dogs being over a year.  Warning signs of hip dysplasia may include an awkward gait, waddling of the hind quarters when walking, stiffness when first getting up from a nap, a clicking sound heard from the hind end, lameness in one or both hind limbs, exercise intolerance, or pain upon petting the hip region.

Diagnostic Options

The diagnosis of hip dysplasia is based on history, physical examination, and radiographic evaluation. A typical symptom history may include any or all of the following: difficulty or stiffness upon rising, using front legs only and dragging rear, "bunny hopping" gait, short stride in rear legs, reluctance to exercise or climb stairs, rear limb lameness, soreness in hips, and waddling gait. The clinical signs commonly begin between five to eight months of age or after skeletal maturity. Some dogs don't have noticeable problems until eight to ten years of age or older. The onset of clinical signs may appear sudden or gradual. This variability is due to the individual severity of the disease as well as pain tolerance of the dog. Observation and physical examination can arouse suspicion of hip dysplasia. However, definitive diagnosis is established by radiographic examination of the dog.

Radiographs are necessary to confirm the diagnosis and evaluate the severity of CHD. In young dogs or in very mild cases, joint laxity may be the only detectable abnormality. Later in the disease, arthritic changes are seen. The standard radiographic position is with the dog lying on its back with both rear legs pulled straight back and parallel to each other. Most dogs with CHD are too painful to tolerate this position awake, so sedation or anesthesia is usually necessary. Proper radiographic positioning is very important to accurately evaluate the hips and to determine the best treatment plan.

The diagnosis of hip dysplasia is based on the evaluation of x-ray images of the pelvis. Only looseness of the hip joint may be seen on the x-ray image in young dogs. As the dog matures, the affected joints develop bone spurs, a sign that the hips are degenerating. Recently, the PennHIP program has emerged as a new scientific method for the early diagnosis of CHD.  PennHIP measures the passive hip joint laxity or "looseness" of the hip ball in the hip socket under sedation or anesthesia. PennHIP is more reliable than standard x-ray images and has the advantage of being accurate on puppies as young as 16 weeks of age.