What is Hip Dysplasia?
Canine Hip Dysplasia (CHD) is a condition that forms in dogs as they grow and results in instability or a loose fit (laxity) of the hip joint (Figure 1). The hip joint laxity can be responsible for hip pain, limb dysfunction, and joint changes. The hip joint is a ball and socket joint and – in some cases – continued, unusual movement of the femoral head (ball) can deform the acetabulum (socket). The long-term result of this condition is 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).
CHD can be caused by many factors; however, hereditary (genetics) is the biggest risk factor. Rapid weight gain and growth can also complicate the development of CHD. Hip dysplasia occurs most commonly in large breed dogs.
How to tell if your dog is suffering from Hip Dysplasia:
The signs of CHD are:
- Lameness (limping)
- Reluctance to stand, jump or go up and down stairs
- Shifting of weight to the front limbs
- Loss of muscle mass on the rear limbs
- Hip pain
Generally, dogs with CHD are divided into two groups showing signs of CHD:
- Group 1: Younger dogs without arthritis, but with significant hip laxity.
- Group 2: Mature dogs that have developed hip arthritis due to CHD.
Dogs can demonstrate signs at any stage of disease’s development, though many may not show any signs at all.
An exam by your veterinarian is the first test that should take place. They will evaluate changes in your dog’s step, and look for evidence of hip laxity. A thorough orthopedic evaluation is important because a number of neurologic and other orthopedic problems can cause issues similar to those seen with CHD.
X-rays are crucial to help diagnose CHD (Figure 3). In order to get the best X-rays, dogs may need to be sedated or placed under anesthesia for proper relaxation and positioning. If the dogs are at least two years of age, the X-rays can be sent to the Orthopedic Foundation of America which can review the X-rays. They will then assess the hips for changes and assign a grade. X-rays with the hip under load/pressure are used to detect breed susceptibility to hip dysplasia as early as four months. However, while many dogs have evidence of CHD on X-rays, it could be a different issue that is causing their pain. This is yet another reason why a proper examination is so important.
There is no best treatment option for CHD. Treatment recommendations will depend on the following:
- Body size and weight
- Degree of discomfort and dysfunction
- X-ray results
- Future, expected function/activity
- Your expectations
- Your budget
Additionally, not all dogs with CHD will need treatment. Approximately 75 percent of young dogs with CHD can maintain function well into their senior years without developing hip pain. Medical and surgical options are available for young and mature pets with CHD. Most dogs are initially treated with medical supervision.
Medical treatment entails a combination of multiple methods to improve your pet’s comfort as much as possible, without surgery, and can include:
- Weight loss and diet management
- Lower-impact activities (like walking or swimming)
- Nonsteroidal, anti-inflammatory drugs
- Physical rehabilitation
- Fish oil supplements
- Osteoarthritis drugs
Dogs in Group 1 generally do not respond as well to medical treatment as the dogs in Group 2. For this reason, surgery by a board-certified veterinary surgeon may be required.
One common surgical procedure is known as juvenile pubic symphysiodesis or JPS. JPS entails the following:
- The goal of JPS surgery is to stop the growth of the pubis (part of the pelvis) to alter the growth/shape of the pelvis.
- Increasing the ball’s degree of coverage by the socket to diminish hip laxity.
It is a relatively minor surgical procedure and it must be performed on puppies less than 18 weeks of age. However, since most puppies do not show signs of CHD, early diagnosis by way of examination and special X-rays is critical.
Another option for young dogs (less than 10 months old) with CHD, but with no arthritic changes, is a double or triple pelvic osteotomy (DPO/TPO) surgery. These procedures involve:
- Cutting the pelvic bone in two (DPO)-to-three places (TPO).
- Rotating the segments to improve coverage of the ball by the socket and decrease hip laxity (Figure 4).
The TPO has been used in dogs for decades. Recent advancements in implant (locking plates and screws) technology allow similar results with only two cuts made in the bone.
Young dogs with evidence of hip arthritis are not ideal candidates for TPO/DPO, nor are dogs with very severe hip laxity. Dogs need to be screened by examination and X-rays to determine if they may benefit from surgery. Dogs that are not a good fit should be managed medically until they are old enough for total hip replacement (THR) or femoral head ostectomy (FHO) surgeries.
Young dogs who are not good candidates for TPO/DPO or JPS, or Group 2 dogs who don’t respond to medical treatment, may benefit from FHO.
This technique involves removing the femoral portion of the hip joint (the ball) to reduce the pain and stretching of the soft tissues around the joint due to laxity (Figure 5).
Following an FHO, a “false joint” develops with the muscles around the hip, now transferring the forces from the leg to the pelvis during limb movement. The goal of an FHO is to relieve the pain associated with CHD, not to recreate normal hip function. For this reason, the procedure is less common in larger dogs.
THR is another option for Group 1 and 2 dogs. This procedure eliminates hip pain and, unlike an FHO, recreates normal hip function. As with humans, canine THR involves replacement of both the ball and socket with metal and polyethylene (plastic) implants (Figure 6). These components are fixated in place with bone cement, metal pegs or “press fit” (bone ingrowth) methods.
What to expect after treatment:
Juvenile Pubic Symphysiodesis (JPS):
Risk of complications after JPS are very low and almost all are minor in nature. Success rates for JPS eliminating hip laxity are high and aftercare is very brief, usually just entailing basic wound/incision care and short-term restriction of activities.
Double Pelvic Osteotomy (DPO)/Triple Pelvic Osteotomy (TPO)
Reported complications after DPO and TPO include:
- Screw loosening
- Change of range of motion in limbs
- Pelvic canal narrowing
The incidence of complications is low and reports of long-term function are expected to be good-to-excellent.
Total Hip Replacement (THR)
THR results in an exceptional chance of improved limb function. Potential complications after THR include:
- Hip dislocation
- Loosening of the implants over time
- Nerve injury
- 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 they have healed (as demonstrated through examination and X-rays), generally six and eight weeks respectively.
Most pets require supervision after surgery to prevent overuse of the leg during the healing process. If necessary, pet owners may use a sling to help their dog with walking in the early stages of recovery. Dogs should avoid stairs, slippery surfaces, and interactions with other dogs. To get back to normal, slowly increase activity after the initial period of restriction.
Femoral Head and Neck Ostectomy
Results after FHO vary and are highly dependent upon patient size and proper post-op physical rehabilitation. While many dogs will have varying degrees of lameness, function should improve when compared with status prior to surgery.
After FHO, pets are encouraged to use the limb as soon as possible in a controlled manner. Physical rehabilitation and controlled exercise to increase hip range of motion are important for the best possible outcome. Keep in mind that it may take up to six weeks or longer after surgery for some dogs to show improvement.
If you have concerns about your dog, and you need to locate a board-certified veterinary surgeon, use the VetSpecialists.com search tool on the website’s homepage. The tool allows you to search for a veterinary specialist, then select the type of animal along with your location by zip code or city name. Contact the hospital of your choice to discuss your pets’ signs and to review whether there is a need for a referral from your primary care veterinarian.