Hip Dysplasia

Hip Dysplasia - Diagnosis, Medical Management, and Surgical Options

Hip dysplasia is a developmental abnormality of the hip joint(s).  It is common in large and giant breed dogs, but can be seen on small breed dogs and cats as well.  It usually occurs secondary to a combination of genetic, dietary, and environmental factors that contribute to excessive laxity (loose soft tissue support) of the hip joint.  This laxity causes secondary inflammation of the joint, subluxation of the hip (the hip partially pops out of joint, see picture), abnormal development of the hip “ball and socket” joint, and eventual arthritis.  The hips of affected dogs are generally normal at birth, but do not continue to develop normally with growth. 

The goal is to identify puppies with hip joint laxity at an early age (ideally before 15-20 weeks of age) so that appropriate intervention strategies (medical and/or surgical) can be started.  JPS is one surgical option that can improve hip conformation and reduce arthritis of the hips long term, but it must be performed before 20 weeks of age (preferably before 15 weeks of age).

Diagnosing Hip Dysplasia (HD) 

Diagnosis of hip dysplasia in adult animals is generally straightforward and involves a combination of a physical exam and x-ray findings that look for classic symptoms and signs of the condition.  Diagnosing hip dysplasia in puppies is more challenging, as they often do not yet have the characteristic changes on x-rays and arthritis has usually not yet developed. Suspicion of HD in puppies is generally based on a combination of the puppy’s breed (large and giant breed dogs are predisposed), physical/orthopedic exam, gait analysis (how the pet walks), and possibly imaging.   Puppies may show signs of hip dysplasia (soreness or gait abnormalities) between 5 and 10 months of age due to pain from joint laxity (however many affected dogs may not show symptoms at this age).  If hip dysplasia is allowed to progress, often dogs will become symptomatic when they are older after osteoarthritis (OA) has developed as a result of joint laxity.  Unfortunately, these symptoms may be dismissed as the pet “slowing down” or “getting old”, when they are actually signs of joint pain and soreness.

Signs of hip dysplasia in young dogs include:

• Reluctance to jump
• Shifting weight to front end
• Atrophy/decreased muscling of rear limbs
• Increased muscling of front legs and chest
• “bunny hopping” or “hula dancing” gait in rear end

Signs of hip dysplasia and arthritis in older dogs include:

• Decreased activity
• Trouble/slow to get up or use stairs
• Reluctance to jump
• Rear limb atrophy/muscle loss and/or lameness
• Getting up with front end first then the back end

If any of these symptoms are seen in your pet, please be sure to address them with your veterinarian promptly. 

During a physical exam, the veterinarian should observe the puppy for lameness, gait/walking abnormalities, muscle tone and range of motion of the limbs, etc.  They may also perform an Ortolani sign or Barden test to look for hip joint laxity.  Both tests can be performed on cooperative puppies.  In a puppy who is suspected of having hip laxity, but is wiggly or not a fan of having their hips manipulated, sedation may be recommended to perform the tests properly.  Keep in mind that the Ortolani sign and Barden test are only useful in young dogs that have not yet developed severe inflammation and thickening of the tissues around the hip joint. 

Radiographs (x-rays) may be recommended to evaluate the bones of the pelvis and hips. 

• Plain or standard radiographs may easily miss hip dysplasia in puppies due to the decreased calcification of the pelvis at this age and the fact that the hip joint can look completely normal but still have excessive laxity.  The x-ray signs of hip dypslasia may not be evident until the puppy is older and more fully developed and/or the x-ray signs of arthritis become apparent.  However, x-rays are still recommended before any surgical interventions to screen for any other abnormalities (previous fractures, malformations, etc).
• OFA radiographs (x-rays) cannot be performed on dogs until 24 months of age to assess the hip joints.  Dogs that have good OFA scores may still have moderate joint laxity and it does not always predict accurately if arthritis will occur.  While OFA radiographs are potentially helpful to screen and certify dogs for breeding purposes, this test does not allow for early detection of hip laxity/dysplasia in dogs under 24 months of age.
• PennHIP (Pennsylvania Hip Improvement Program) x-rays are much better at detecting hip laxity than other types of radiographs.  A veterinarian certified by PennHIP uses a special device to x-ray the hips while the puppy is under anesthesia.   The images are submitted to PennHIP for evaluation and assigned a distraction index (DI). The DI is correlated with the likelihood of future arthritis development.  The limitations of PennHIP radiographs include: must be referred to a certified veterinarian, puppy must be 16 weeks of age, it can take about a week to get results back.  The cost and delay in results may preclude this test from being used to screen puppies for hip joint laxity when considering a JPS surgery.

Medical Therapy

            Once hip laxity/hip dysplasia and/or arthritis have been identified, or if the pet is deemed to be high risk for these conditions, medical management should be started.  This should include maintaining a lean body weight (weight reduction if pet is overweight), making sure any puppies under 18 months of age are on a quality large breed puppy food, joint supplements (Dasuquin can be started as early as 6 months of age in at-risk dogs), pain management if needed, avoid high impact activity (jumping, running), encourage low impact activity (walking, swimming), referral for physical therapy, laser therapy, etc.   Spaying of large breed dogs should be delayed until 10-11 months of age if possible.  Neutering should be delayed until 18 months of age if possible.  If there is a risk of breeding in a male dog, a vasectomy can be performed to prevent breeding but maintain the male sex hormones until a neuter can be performed at 18 months of age (or if a full neuter is not desired).  A vasectomy should be done concurrent with the JPS surgery in male dogs.  Breeding is not recommended in these dogs, as a large part of this condition is genetic. 

Surgical Intervention

            Two joint preservation surgeries can be performed on young dogs to try to normalize and preserve the hip joint – JPS and DPO/TPO. 

JPS is a simple procedure with few complications that can be performed by a non board certified veterinarian.  There are multiple studies that demonstrate its effectiveness.  However, it must be performed before 20 weeks of age. 

Double or Triple Pelvic Osteotomy (DPO or TPO) is invasive (involves cutting and plating the pelvis in 2-3 locations), must be performed by a boarded surgeon, expensive, has a higher risk of complications (some serious), and lacks strong evidence on its effectiveness.  If performed, the patient should be screened rigorously to ensure that they are a good candidate.  Dogs are usually between 6 and 10 months of age when this procedure is performed.

FHO (Femoral Head Ostectomy)        

Once a dog has established hip dysplasia and arthritis, if significant subluxation or other degenerative changes are present, FHO (femoral head and neck ostectomy) can be considered. This is considered a salvage procedure and should be discussed if the pet is still painful or otherwise negatively affected despite aggressive medical management.  It is best if the pet is not overweight and still has sufficient muscling around the joint to provide stability after surgery.  Removing the femoral head (ball part of the ball and socket joint of the hip) eliminates the painful bone on bone rubbing that occurs.  The muscle and soft tissues around the hip provide stability and a pseudo-joint forms.  Most pets are able to regain normal function and activity after recovery from the surgery, though the limb will be slightly shorter than the opposite leg so a slight “hitch” in the gait may be seen.

JPS (Juvenile Pubic Symphysiodesis)

         Large or giant breed puppies under 20 weeks of age (ideally under 15 weeks of age) with a positive Ortolani or Barden test and/or symptoms of mild to moderate hip joint laxity are candidates for JPS. Dogs with severe hip joint laxity may not benefit as much from the procedure, as the pelvic rotation may not be enough to “catch” a severely out of socket femoral head. 

The JPS involves removing or destroying the growth plate at the pubic symphysis (bottom of the pelvis) early in life to stop bone growth in this location.  This then prevents widening of the bottom of the pelvis as the remainder of the pelvis continues to grow. Accordingly, as the rest of the pelvis matures there is rotation and 'overgrowth' of the top part of the pelvis over the hip joints. This increased coverage of the femoral heads allows deepening of the socket of the ball and socket joint of the hip.  The hip is more stable, has less abnormal motion (subluxation), and arthritis is less likely to occur. 

         The JPS procedure should ideally be performed at 12 weeks of age.  After this, for every week it is delayed, there is about a 10 degree loss of rotation of the pelvis.  Every effort should be made to perform the surgery before 15-18 weeks of age. There is still some measurable benefit of performing the surgery up to 20 weeks of age, especially in giant breed dogs.  It is not recommended in dogs over 20 weeks old.

         Complications are uncommon and generally mild.  Seromas (fluid pockets) may occur, but tend to be self-resolving and mild.  Exercise should be restricted for 2-3 weeks after surgery, otherwise home care is similar to other soft tissue procedures. 

         Several studies show the benefits of performing JPS in dogs with confirmed or a high suspicion of mild to moderate hip joint laxity.  The notable statistics are listed below:

1. 25% of JPS treated dogs (done at 15-18 weeks) had signs of arthritis by 2 years of age, vs 83% of control dogs who did not have surgery
2. The percentage of dogs with more moderate to severe x-ray changes of hip dysplasia at skeletal maturity was significantly higher for the control group not treated w/ JPS
3. For Ortolani positive dogs in which JPS was performed, many of the variables related to pelvic rotation improved and there was a 74% reversal to Ortolani negative status.  Average arthritis level for JPS dogs remained stable at 11%, while non JPS control dogs had a significant increase of average arthritis level to 55%.
4. “Success” was obtained in 85% of dogs that had JPS performed before 18 weeks of age, whereas success was obtained in just 18% of dogs that had JPS performed after 18 weeks of age