Cats and dogs with OA can have different presentations. Dogs often develop OA because of an underlying condition (eg, joint dysplasia, cruciate disease, luxating patellae) that can lead to joint pathology and pain.3 Cats are often presented with primary OA (ie, no underlying disease causing pathology); in one study, a potential underlying cause of OA could only be found in 11% of cats.4
Cats often do not show abnormalities related to OA on physical examination, making diagnosis challenging. Diagnosis relies heavily on signs reported by the pet owner5; it is thus important to obtain a thorough patient history and be aware of changes in the patient. Asking specific questions about comfort, jumping, grooming, and activity level at home can help assess for possible signs of OA. Awareness of the unique presentation of OA in cats can help with early diagnosis and treatment.
Radiographs can help confirm clinical signs that may be attributed to joint disease, monitor changes, and determine the degree of joint disease6; however, survey radiographs may not definitively determine the type of joint disease or inciting cause. Thorough patient history and physical examination are key to diagnosis. Arthrocentesis with cytologic evaluation can help differentiate sepsis, degenerative change, immune-mediated disease, and neoplasia if change is seen on radiographs but the underlying cause is undetermined.
OA management typically involves weight loss, activity modification with consistent exercise, and pain control. OA cannot be cured or reversed. The goal of treatment should be to manage clinical signs, including adequate pain management, and slow progression.7 Pain should be managed first, so patients can become more active, resulting in weight loss and increased mobility.7
Although NSAIDs are the mainstay treatment in dogs with OA, long-term use is limited in cats in the United States, making pain management in cats with chronic disease challenging. Many older cats with OA have concurrent renal disease, precluding use of an NSAID.
Alternative medications include gabapentin, tramadol, and amantadine. These drugs in conjunction with disease-modifying agents (eg, polysulfated glycosaminoglycan) and supplements (eg, glucosamine/chondroitin, omega-3 fatty acids) should be considered in cats with OA. Alternative methods of treatment, including rehabilitation, can also play an important role in managing chronic OA.
There are no level 1 evidence studies assessing most oral medications or laser therapy for treatment of OA pain in cats. In addition, there are few FDA-approved long-term medications available to treat OA in cats, making management significantly more challenging than in dogs.
Frunevetmab, a monoclonal antibody that targets nerve growth factor, has been FDA-approved for use in cats in the United States. Preliminary studies for this new class of pain relievers show possible treatment for feline OA pain.8,9 Clinical trials showed minimal effects on the liver, kidneys, and GI system; dermatologic adverse effects were most common.8,9 Frunevetmab is a monthly injectable medication that may be more easily administered to cats compared with daily oral medications. Further study and evaluation are needed to determine efficacy.
Surgical intervention, including total hip replacement and femoral head and neck ostectomy, is often considered in patients with hip OA, but surgery was not appropriate for this patient because of degenerative stifle changes and severe obesity.
After pain is controlled, activity can be modified to include more low-impact activities, as they are better tolerated by patients with OA. Increasing activity as tolerated should be a goal in sedentary patients.