Hip Dysplasia is a Treatable Hereditary Disorder in Cats

Hip dysplasia in cats is a hereditary disorder caused by a physical malformation in the ball-in-socket joint in the cat's hips/pelvis that worsens over time, increasing the likelihood of hip dislocations. This disorder is believed to be caused by inheriting multiple different gene mutations that together affect how the hip joint develops. 

Hip dysplasia is typically not present at birth but develops over time as your cat grows, and is often diagnosed in young cats between 3 months to 3.5 years old. Some early warning signs you may notice include a decrease in your cat's activity, and they may try to avoid using stairs or jumping. 

The hip joint of cats with this type of developmental dysplasia are shallower than normal, leading to the leg (femur) not fitting securely in the hip joint (acetabulum). This can lead to partial or complete dislocation of the hip joint and pain.

Interesting fact:  In cats, the most common secondary effect of hip dysplasia is a change in the shape of the bones of the head of the femur (the ball) and the rim of the acetabulum (the socket). In dogs with hip dysplasia, it is the femoral neck (the part of the bone that connects the "ball" of the femur to the long straight part) that changes over time. 

Hip dysplasia affects ~6-10% of domestic shorthair cats (which make up over 95% of cats in the United States) and ~20% of purebred cats. Of the purebred cats, Maine Coones have the highest risk, at ~37%, and both girls and boys are equally affected.

Maine coons are also at a higher risk for hip dysplasia due to being one of the largest breeds of cats. This means they weigh more, causing them to put more pressure on their joints. Larger cat breeds and any overweight cat have a higher risk of showing symptoms of hip dysplasia. 

Other breeds of cats at higher risk of hip dysplasia include the Devon Rex, Siamese, Himalayan, and Persian. There is not sufficient data to determine the risk of hip dysplasia in domestic longhair cats. 

Hip Dysplasia is Hereditary

Purebred cats have at least twice the risk of developing hip dysplasia compared to domestic shorthair cats because they typically have a smaller pool of genes to draw from. This means offspring are more likely to inherit a mutation that contributes to hip dysplasia. Selectively breeding cats with normal hips can reduce the risk of hip dysplasia. 

One study found that focusing on breeding Maine Coones with healthier hips showed an over ~65% reduction in offspring with hip dysplasia when comparing parents with their 8th-generation great-grand kittens.  

Knowing your cat's pedigree can help you remain alert to the risk of hip dysplasia, but even if it’s unknown, there are signs you can look out for in your cat's history. If your cat has had a knee dislocation (patellar luxation), it is three times more likely to have hip dysplasia as well. Known trauma to the joint, such as a fall, can also lead to the dislocation of the hips that are part of hip dysplasia.

Symptoms of Hip Dysplasia in Cats

Most of the time, hip dysplasia will occur in both hips (bilaterally) and may be detected through the gradual onset of one or multiple symptoms:

• Limping or dragging of the feet (lameness)
• Unwillingness to put weight on their hind legs
• Significant changes in mobility after weight gain
• Difficulty using the litter box in normal ‘squatting’ positions
• Avoidance of using the stairs or jumping
• Howling/vocalizing when walking and resting
• Licking/chewing on the hips
• One leg looks shorter than the other
• Decrease in overall activity
• Decrease in appetite due to pain
• Changes in temperament (like aggression to being touched)
• Decreased activity at night

The looseness of the bones in the hip joint can cause chronic pain conditions over time as the leg bone slipping out wears down the soft tissue in the joint, causing the bones to rub together. This is known as osteoarthritis and is a common side effect of hip dysplasia. 

Detection of Hip Dysplasia

Even though cats are champions at hiding their pain, your veterinarian can use an X-ray to observe your pet's bones and visually confirm hip dysplasia. Your veterinarian may also check that your cat’s legs have the full range of motion during a physical exam by moving your cats legs to see how they sit in the joint and feel for any ‘grinding’ (called crepitus). Limited range of motion of the legs would lead your veterinarian to consider a diagnosis of hip dysplasia. This can be tested while the cat is awake or sedated. 

Treatment Options for Cats with Hip Dysplasia

Most cats with hip dysplasia display behavioral changes before they reach the point of a hip dislocation. This means this condition is often caught early and managed without surgery. 

Some of these options include weight management, physical therapy exercises, environmental changes, and acupuncture. Your veterinarian may also be able to show you some massage techniques, including rubbing your cat's belly and gently kneading their back!

The first line of defense against worsening hip dysplasia would be controlling your pet's weight. This can be through diet changes or ensuring your cat remains active. A cat that is running and jumping around will develop the muscles in their legs and hips, which then support the hip joints by keeping the bones in position. 

If your cat likes to lounge around, you can use treats, toys, or even put their food on a higher surface to encourage movement and muscle development. Consistent gentle exercise, such as taking a walk or directing them with a laser pointer, at least a few minutes daily, can have significant long-term benefits for cats with hip dysplasia. 

Having your cat walk across soft, uneven surfaces like couch pillows requiring them to balance can help strengthen their coordination, flexibility, and legs. The exception is if your cat is experiencing difficulty walking or lameness, then focus on keeping your cat as comfortable and spoiled as possible!

If it is determined that your cat’s leg is currently completely dislocated, your veterinarian will perform a procedure called a reduction. This procedure has a 50% success rate and consists of the veterinarian placing the leg back into the hip joint. To keep the leg in place, a bandage or wrap will be placed for up to two weeks, and pain meds will be used to keep your cat as comfortable as possible while the joint heals.

Although rare, if reduction does not work, your cat has had multiple hip dislocations, or they are experiencing significant chronic pain, your veterinarian may also suggest surgical options. These include a total hip replacement (THR), joint stabilization surgeries like round ligament reconstruction (called toggle-pinning) or a modified hip-toggle, or even removal of some bone in a femoral head/neck ostectomy (FHNO). All these procedures require anesthesia and will not eliminate the risk of arthritis in the hips, which often appears months to years after the procedure. 

Whichever option you and your veterinarian choose, it is important to keep your cat calm, comfortable, and confined, such as in a crate, after treatment so they cannot hurt themselves by jumping or running.

During the recovery period, there are multiple things you can do to assist in your cat's comfort. Your veterinarian may also suggest some lifestyle changes for your cat, which may include weight control or adding in some supplements. 

While your cat is healing, it is the perfect time to rearrange some furniture, so your cat can take steps instead of leaps to run around your space. Add ramps around your home to make your cats' favorite ledges, beds, and windows accessible. An alternative to ramps are small steps and switching to a litterbox with a low and wide opening. This can help them overcome any reluctance to jump while assisting in building and maintaining muscle after their recovery period.  

Hip dysplasia is often accompanied by osteoarthritis, which can appear months to years after a hip displacement. This leads to some overlap in the pain management of hip dysplasia and arthritis as both may be prescribed some pain medication like the NSAIDS Meloxicam and Robenacoxib. 

Long-term NSAID use can cause liver damage and affect the kidneys. Some alternative methods of pain management, like CBD, target the joint inflammation that causes the discomfort. In one case study, there was a subjective 38% decrease in their pet’s osteoarthritis pain after the use of CBD and THC as directed by a veterinarian.

A variety of supplements can target and improve your cats' symptoms. Glucosamine and chondroitin have been shown to help with joint pain. They do this by helping build and maintain the soft tissue in the joints, which prevents the bone on bone contact. Adding Omega-3 into your cats' diet, through food containing fish or as an additional supplement, can also help reduce swelling, improve healing, and may assist in weight loss in obese cats. 

Hip dysplasia is a genetic condition that disproportionally affects purebred cats. Often identified through behavioral changes, this condition can be treated both with and without surgery.

Management of hip dysplasia includes muscle-building activities, weight management, and pain control under the direction of your veterinarian. Hip dysplasia in cats is treatable, and cats affected by this condition can still live happy, long lives under the careful care of their owners.