Hip Dysplasia in Dogs


The term dysplasia means abnormal growth, thus hip dysplasia means abnormal growth or development of the hips.  Hip dysplasia occurs during a puppy's growing phase, usually a large breed puppy, and essentially refers to a poor fit of the ball and socket nature of the hip.  The normal hip consists of femoral head, which is round like a ball and connects the femur to the pelvis; the acetabulum, which is the socket of the pelvis; and the fibrous joint capsule and lubricating fluid that make up the joint.  The bones (femoral head and acetabulum) are coated with smooth cartilage so that motion is nearly frictionless, and the bones glide smoothly across each other's surface.                             

Hip dysplasia is a common condition of large breed dogs.  Many dog owners have heard of it, but anyone owning a large breed dog or considering a large breed dog should become familiar with this condition.  The larger the dog, the more likely the development of this problem becomes, particularly as the dog ages and loss of mobility/arthritis pain become important life quality issues. 

When a dog has hip dysplasia, the ball and socket do not fit smoothly.  The socket is flattened and the ball is not held tightly in place, thus allowing for some slipping.  This makes for an unstable joint, and the body’s attempts to stabilize the joint only end up yielding arthritis.

Obviously, different individuals may have various degrees of dysplasia.  A dog's weight makes a difference (a lighter dog can more easily tolerate a more abnormal hip joint).  The muscle mass supporting the joint is more significant in a younger dog and helps reduce the stress directly on the bones.  Still, some dogs have shocking radiographs and virtually no symptoms, while others show relatively subtle changes and are very uncomfortable.  It is not known why there is not a better correlation between radiographs and actual pain.

Do not expect a dog with dysplasia (or any other chronically painful condition for that matter) to cry or whine in pain.  Instead discomfort is shown with reduced activity, difficulty rising or lying down or going up stairs.  A characteristic swivel of the hips is seen from behind and classically stairs are taken in a bunny hop fashion.

The primary cause of hip dysplasia is genetic but inheritance of this trait is not as simple as a dominance/recessive relationship like we study in high school biology.  Normal dogs can breed and yield dysplastic offspring as the condition may skip generations.  Furthermore, dogs with a genetic picture conducive to hip dysplasia still must contend with other factors such as level of exercise at an early age, nutritional factors, hormonal/neutering factors, and other environmental situations.

Preventing hip dysplasia primarily focuses on breeding dogs with normal hips.  The problem with this approach is that dogs often do not develop signs of hip dysplasia until well after they have been bred.  A genetic test would be of great value in dog breeding, but currently, there is only such a test available for Labrador retrievers; identifying dogs with less than stellar hip quality to exclude them from breeding is done via OFA and PennHip certification.

It is important to consider the breed of dog when choosing a puppy for many reasons, including potential genetic orthopedic problems.  Hip dysplasia is typically a problem for large, stocky dog breeds.  Small dogs and lean, slender breeds such as sighthounds rarely develop hip dysplasia.  If you have settled on a breed with an issue with hip dysplasia, be aware of the parents' certification process.

Other than selective breeding, managing different factors in hip dysplasia development is possible when raising a predisposed puppy that may help make the genetic issues less severe.

Nutritional factors are important in developing hip dysplasia.  For example, it has been popular to try to nutritionally push a large breed puppy to grow faster or larger by providing extra protein, more calcium, or even just extra food.  Practices such as these have been disastrous, leading to bones and muscle growing at different rates and creating assorted joint diseases of which hip dysplasia is one.  One study showed that when puppies of hip dysplasia prone breeds were allowed to free feed, two-thirds went on to develop hip dysplasia while only one-third developed it when the same diet was fed in meals.  Another study showed German Shepherds were nearly twice as likely to develop hip dysplasia if their adult weights were above average.  Studies such as these have led to puppy foods designed for large-breed puppies, where the optimal nutritional plane is lower than for small-breed puppies.  After puppyhood, maintaining a lean body condition seems to help lessen arthritis signs.

The precise nature of the proper preventive exercise regimen is yet undefined.  One study showed that puppies had an increased risk for hip dysplasia if they were allowed to run up and down stairs before age three months freely.  Decreased risk was found in puppies allowed off leash exercise, such as in the back yard, before age three months.

There is some controversy about the effect of spay/neuter before puberty.  Male dogs rely on testosterone to stop bone growth and early neutered males will grow taller as their bones are grow for a longer period if testosterone is removed early.  This may lead to a predisposing disparity in the growth of bone and muscle.  There appear to be predisposing factors for early spay as well, assuming the dog has the genetic predisposition.  How much added predisposition comes with early spay/neuter and to which breeds remains of great controversy, and, of course, delaying spay leads to other issues (such as a strong predisposition to developing mammary tumors).

There are two reasons to pursue testing: to explain a dog's discomfort/rear weakness or to screen a dog for breeding purposes.  If a dog is not going to be bred and is not in any apparent discomfort, there may be no benefit to looking at the conformation of the bones in a radiograph except possibly to look back at a future time to get a sense for the progression of bony changes.

The first step in diagnosis is an examination.  Your veterinarian will likely extend the dog's hind leg backward to check for pain, as hip dysplasia causes pain on hip extension.  The dog may be asked to walk around to demonstrate the possible hip swivel.  Another test involves the dog lying on its back with a hind leg perpendicular to the body.  As the leg is moved from perpendicular to the body, a dysplastic hip will generate a pop as the femoral head slips to the center of the acetabulum.

The proper confirmation of hip dysplasia comes with radiography.  The dog must be radiographed on their back with both legs positioned straight down.  This posture is painful to a dog with dysplasia so to get maximum cooperation from and comfort for the patient, sedation is needed.  The seating of the femoral heads in the acetabular sockets is examined and assessed for arthritis.

When purchasing a puppy, particularly one of a larger breed, often the parents will be listed as “OFA Good” or “OFA Excellent.” This means that the breeder has had the hips of the parent dogs certified by the Orthopedic Foundation for Animals.  The OFA is an organization with the goal of reducing the incidence of hip dysplasia (though now it is also possible to obtain certification for elbows, thyroid function, and other issues). The idea here is that a dog for breeding can have radiographs taken at age 24 months.  The radiographs are sent to the OFA for review by several independent radiologists, where they are graded.  Hips that are rated as “good” or “excellent” receive a registration number.  Offspring of OFA certified parents would be less likely to develop dysplasia themselves, however, it is essential to realize that a dog with excellent hips at age two may not have such excellent hips at age five, seven, or ten.  OFA certification is no guarantee that a dog will not develop hip dysplasia symptoms in the future and does not guarantee that the offspring will not develop hip dysplasia but, as mentioned, until DNA test for hip dysplasia is developed parental certification is the best we can do.

There are many surgical options for hip dysplasia, and it is crucial to understand which patients benefit from which surgery.  Some surgical procedures are controversial, and some are not.  All will entail a recovery period as well as expenses.  Both hips need not necessarily be treated surgically; treating one hip is often enough to yield good results.  Hip surgery is relatively expensive, and a surgery specialist may be required, depending on the procedure.  If you are considering surgery for your dog, these are the procedures to know about.

This surgery is performed on young puppies before age five months, so it is generally done as a preventive procedure before it is known if the puppy will indeed have dysplastic hips but after hip laxity has been detected.  The pubic symphysis is the cartilage seam connecting the right side of the pelvis to the left side.  As an individual matures, this cartilage converts to bone and the two halves of the pelvis fuse permanently.  This surgery prematurely seals the symphysis, resulting in rotating the developing hip sockets into a more normal alignment.  This is the same re-configuring as the TPO above but instead of doing the reconfiguring with surgery, it is done by directing the puppy’s bone growth.  The window is very narrow for this procedure so if a puppy is a predisposed breed it may be worth getting screening radiographs around age four months even though no physical discomfort has developed.  It may be worth having this preventive procedure while the puppy is still at an age to benefit from it.

No matter which, if any, procedure is selected, it is vital to get an idea of expenses, recovery procedure, and what is entailed from your veterinarian and the surgeon before making a decision.

Non-surgical treatment of hip dysplasia is essentially the same as non-surgical treatment for any other type of arthritis.  There are nutritional supplements to help repair cartilage, pain medications, and anti-inflammatory medications.  Physical therapy and massage are also necessary and helpful in non-surgical joint treatment.  There is no medical way to reverse or prevent hip dysplasia; the medications described are for pain management.