Hip dysplasia (HD) is an abnormal development or malformation of the hip joint. The feline hip joint functions as a ball-and-socket mechanism, where the femoral head fits into the acetabulum of the pelvis. In cats with HD, this fit is loose or misaligned, leading to joint instability and subluxation. This mechanical friction inevitably causes degenerative joint disease, or osteoarthritis, resulting in chronic discomfort. Although HD is more commonly discussed in dogs, it is a recognized orthopedic disorder in cats that significantly impacts their quality of life, often presenting in subtle ways.
Identifying Subtle Signs and Risk Factors
Cats often mask signs of pain, meaning the symptoms of hip dysplasia are usually gradual and understated. Owners may first notice a reluctance to engage in typical feline behaviors, such as jumping onto high surfaces. Stiffness is common, particularly after rest or upon waking, which can manifest as difficulty rising or moving with an unusual gait.
Changes in a cat’s daily habits also signal chronic hip discomfort. These changes include reduced interest in play or decreased overall activity. Owners may also notice a decrease in grooming, especially around the hindquarters, due to the pain of maneuvering. Furthermore, some cats may avoid using a standard litter box and opt for a lower-sided area, as squatting becomes uncomfortable.
The primary cause of feline hip dysplasia is genetic, making certain purebred cats significantly more susceptible. Breeds like the Maine Coon, Persian, and Himalayan have a higher prevalence, with incidence rates sometimes exceeding 24% in these populations. Secondary factors influence the severity and onset of clinical signs. Obesity is a major factor, as it puts excessive mechanical stress on the compromised joint, accelerating degenerative changes and increasing discomfort.
Veterinary Diagnostic Process
Diagnosis begins with a thorough physical examination and a discussion of the observed signs at home. During the exam, the veterinarian carefully manipulates the cat’s hips to assess the range of motion and check for joint laxity. They may look for an “Ortolani sign,” which is a palpable or audible click indicating the femoral head moves out of and back into the socket.
The definitive diagnosis relies on diagnostic imaging, typically X-rays (radiographs). These images allow the veterinarian to visually assess the shape of the femoral head and the acetabulum, confirming the degree of joint misalignment and the presence of secondary osteoarthritis. Precise positioning is required to capture high-quality images. Because cats may tense up or resist due to pain, light sedation or general anesthesia is often necessary for the procedure.
Radiographic findings objectively assess the severity, often by measuring the depth of the acetabulum or the degree of subluxation. Measurements, such as the Norberg Angle, help determine the best course of management. Imaging also helps rule out other orthopedic conditions that cause similar signs, such as spinal cord inflammation or traumatic injury.
Conservative Management Strategies
For many cats with hip dysplasia, conservative management methods are highly effective in controlling pain and maintaining quality of life. Achieving and maintaining a healthy body weight is paramount, as excess weight increases the load on the hips, exacerbating discomfort and the rate of joint degeneration. A veterinarian can help establish a targeted weight loss plan through controlled diet and appropriate caloric intake.
Pharmacological support often includes non-steroidal anti-inflammatory drugs (NSAIDs), which mitigate pain and reduce joint inflammation. NSAIDs are highly effective but must be prescribed and monitored by a veterinarian due to the specific metabolic differences in cats. Joint supplements, commonly containing glucosamine and chondroitin, are recommended to support cartilage health and joint fluid viscosity, although results can vary.
Environmental modifications focus on making the cat’s daily routine less physically demanding. Owners can install ramps or steps leading up to favorite resting places, such as beds or windowsills, to reduce jumping. Providing low-sided litter boxes minimizes the uncomfortable squatting posture. Ensuring readily available, soft bedding offers cushioning for resting joints. Gentle, controlled physical therapy, such as passive range-of-motion exercises, helps maintain muscle strength and flexibility around the affected joint.
Surgical Treatment Options
Surgery is considered when conservative management fails to adequately control the cat’s pain or when hip dysplasia severely impairs mobility. Two main surgical procedures offer long-term solutions for painful, unstable hip joints. The first is a Femoral Head Ostectomy (FHO), a salvage procedure involving the surgical removal of the femoral head and neck.
The FHO procedure eliminates painful bone-on-bone contact by allowing a “false joint” to form, made of fibrous and scar tissue. This pseudo-joint is supported by surrounding muscles. While limb function is altered, the procedure successfully removes the source of chronic pain. Cats, being relatively light, often adapt well to this procedure, frequently returning to a good level of activity.
The second surgical option, Total Hip Replacement (THR), involves replacing the diseased natural hip joint with prosthetic components made of metal and polyethylene. THR aims to restore normal joint mechanics and function, often yielding a positive prognosis for pain-free mobility. This procedure is more complex and costly than an FHO, typically reserved for cats with severe, debilitating dysplasia or those requiring higher limb function.