By Mindy Cohan, VMD
Hip dysplasia is one of the most common skeletal disorders seen in dogs. The condition is characterized by a malformation of the coxofemoral (hip) joint.
Instead of the normal tight fit between the acetabulum (cup or socket) and femoral head (ball), patients with this condition suffer from a laxity within the joint. The malformation is a result of both genetic and environmental factors.
Hip dysplasia is seen more frequently in large breed dogs such as German Shepherds, Golden Retrievers, Labrador Retrievers, St. Bernards, and Rottweilers. Although seen in smaller dogs, the prevalence is lower and the symptoms related to hip dysplasia are often less severe.
Recognizing the clinical signs of hip dysplasia is important for early intervention and pain mitigation.
Dogs with hip dysplasia often become noticeably less active. Pet parents may notice their dog sleeping or resting more, showing less enthusiasm to go for a walk, and having decreased interest or stamina to play fetch. It is important to mention your dog’s decreased activity to his or her veterinarian. Unfortunately, many people attribute their dog’s sedentary nature to the effects of aging, when in fact the dog might be suffering from pain associated with hip dysplasia.
For dogs, the hind legs play a vital role in their ability to climb stairs and jump. As inflammation develops secondary to hip dysplasia, dogs develop pain and eventually also suffer from a decreased range of motion within the joint. Pet parents might initially notice a pet’s hesitance to jump into a car or walk up stairs. Eventually, the pet may simply refuse these activities and become reliant upon assistance.
As the effects of hip dysplasia progress, owners might notice their dogs having increased difficulty standing up from a lying position. The slowness with which a dog stands up often correlates to the length of time he was recumbent. Difficulty rising is often most apparent first thing in the morning after the dog has been sleeping throughout the night. With activity during their waking hours, dogs can “warm out” of their stiffness.
The surface on which a dog has been resting can also impact the ease with which he can rise. Carpeting affords much better traction than hardwood, tile, or linoleum surfaces. Measures can be taken to improve your dog’s footing and prevent slippage or falls. Carpet runners on wood stairs can increase the mobility and well-being of a dog with hip dysplasia. Area rugs with no slip backing should be used in areas frequently traversed by the dog throughout the house.
“Bunny hopping” refers to the abnormal change in gait sometimes exhibited by a dog with hip dysplasia. It is so named because dogs are seen lifting both hind legs simultaneously like a jumping rabbit. Bunny hopping can be observed when dogs are walking, running, and climbing or descending stairs. According to Dr. Melissa Hobday of the Veterinary Specialty and Emergency Center in Levittown, Pennsylvania, “The characteristic bunny hopping gait is thought to be an attempt to decrease pain in the coxofemoral joints by dividing the forces on each hip in half during weight-bearing and propulsion by using both legs together.” It is important to distinguish bunny hopping from jumping or pouncing activity that can be associated with play or hunting behaviors.
Depending on the severity of a dog’s hip dysplasia and his activity level, pet parents might observe intermittent or continuous lameness in his hind legs. Over time, the abnormal wear and tear of the joint leads to bone proliferation. The normally “C-shaped” socket becomes flattened and shallow while the head of the femur bone loses its smooth ball-shaped appearance and begins to resemble a mushroom. The subsequent inflammation and pain can result in mild favoring or a non-weight bearing lameness of a hind limb.
Dogs with hip dysplasia can exhibit discomfort when the hips are touched by family members, or manipulated by a veterinarian. In the early stages, as the ball pops out of the cup-shaped socket, tiny fractures occur to the rim of the socket and the soft tissue structures surrounding the hip joint become stretched. These changes can manifest as pain in dogs as young as 4 months of age.
As dogs age, hip dysplasia results in the breakdown of cartilage, which serves as a shock absorber for joints. The bone beneath the damaged cartilage also undergoes changes. These structural changes lead to inflammation and the condition known as osteoarthritis. While early X-rays show a normally shaped ball and socket that are misaligned, later X-rays reveal significant bone remodeling of both structures.
Recognizing the early signs of hip dysplasia and taking action are important to slow the progression of irreversible joint disease. Studies have shown that maintaining a pet’s healthy weight can significantly reduce the incidence and severity of osteoarthritis. Exercise modification is also important with light to moderate movement recommended instead of strenuous activity.
In addition to consulting your dog’s veterinarian about medication to alleviate the discomfort caused by hip dysplasia, pet parents can also make adjustments to maintain their dog’s quality of life. As mentioned previously, household modifications such as carpet runners on stairs and on slippery floor surfaces can greatly enhance a dog’s mobility and safety. Ramps are available to aid a dog’s access to vehicles. Ramps can also be built to enable a dog to avoid stairs when exiting the home. Well-cushioned bedding should be provided throughout the home.