Canine Hip Dysplasia (CHD) is a condition that begins in dogs as they grow and results in instability or a loose fit (laxity) of the hip joint (Figure 1). The hip joint laxity is responsible for potential clinical signs (symptoms) of hip pain and limb dysfunction and progressive joint changes. The hip joint is a ball and socket joint and continual abnormal movement of the femoral head (ball) deforms the acetabulum (socket). The long-term response to this joint laxity is the progressive loss of cartilage, the development of scar tissue around the joint, and the formation of osteophytes (bone spurs) around the ball and socket (Figure 2).
The cause of CHD is multifactorial; however, hereditary (genetics) is the biggest single risk factor. Rapid weight gain and growth through excessive nutritional intake can complicate the development of CHD. Hip dysplasia occurs most commonly in large breed dogs.
The symptoms of CHD are lameness (limping), reluctance to rise or jump, shifting of weight to the forelimbs, loss of muscle mass on the rear limbs, and hip pain. Generally, divide dogs with CHD into two groups showing symptoms of CHD:
Group 1: Younger dogs without arthritis, but with significant hip laxity
Group 2: More mature dogs that have developed hip arthritis due to CHD
Dogs may show symptoms at any stage of disease’s development, although many dogs with CHD do not have any obvious symptoms.
Examination is the first test and includes an evaluation of gait changes and evidence of hip laxity. A thorough orthopedic evaluation is critical because a number of neurologic and other orthopedic problems cause symptoms similar to those seen with CHD. X-rays are important to help diagnosis CHD (Figure 3). In order to get the best X-rays, the dog may need to be sedated or anesthetized for proper relaxation and positioning. The Orthopedic Foundation for Animals, a screening agency for canine hip dysplasia, will certify a dog after two years of age. Stress radiographs are used to detect breed susceptibility to hip dysplasia as early as four months. However, many dogs have evidence of CHD on X-rays, yet another problem causes their symptoms; which is why proper examination is so critical.
Risk of complications after JPS are very low; almost all are minor in nature. Success rates for JPS eliminating hip laxity are high and aftercare is very brief, usually just entailing basic incision care and short-term activity restriction.
Reported complications after DPO and TPO include screw loosening, change in limb range of motion, and pelvic canal narrowing. However, the incidence of complications is low and reports of long-term function are expected to be good to excellent.
THR results in an excellent chance of markedly improved limb function. Potential complications after THR include infection, hip dislocation, “loosening” of the implants over time, nerve injury, and femur fracture.
Following both DPO/TPO and THR, the dog’s activity should be restricted to leash exercise outdoors and confinement to a small area indoors until the procedures are deemed healed (via examination and X-rays), generally six and eight weeks respectively. Most pets are weight bearing soon after surgery and require supervision to prevent overuse of the leg during the healing period. If necessary, use a sling for initial assistance with walking. The dog should avoid stairs, slippery surfaces and interactions with other dogs. To get back to normal, slowly increase activity after the initial period of restriction.
Results after FHO vary and are highly dependent upon patient size and proper postoperative physical rehabilitation. While many dogs will have varying degrees of lameness, function should improve when compared with preoperative status. After FHO, pets are encouraged to use the limb as soon as possible in a controlled manner. Aggressive physical rehabilitation and controlled exercise to increase hip range of motion are essential for an optimal outcome. It may take up to six weeks or longer after surgery for some dogs to show improvement.