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Veterinarian Technician January 2013 (Vol 34, No 1)

Degenerative Joint Disease in Cats

by Jessica Erace, LVT

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    Degenerative joint disease (DJD) is a commonly recognized cause of pain and decreased quality of life in older and geriatric dogs. Less well known is the effect of DJD on cats. Based on research in the past 10 years, DJD (more specifically, osteoarthritis) is a relatively common radiographic finding in cats.1–5 However, the disease and its effects on quality of life are underrecognized in cats. With many cats living well into their teens, feline geriatric care is increasingly a part of veterinary practice; therefore, DJD—perhaps the most common disease of domestic cats2—should be acknowledged as a real concern in aging cats.

    The disparity between joint care in dogs and the general lack of it in cats may be due to the difference in the presentation of DJD (i.e., the clinical signs) between dogs and cats, the difficulty of diagnosing the disease in cats, and the limited treatment options in cats.

    The Affected Population

    Much of the research on DJD and osteoarthritis in domestic cats has involved subjects that are 6 years of age and older.1–5 Studies involving subjects with a wide age range have shown a significant correlation between age and the presence of DJD.2,4,5 Because of the high rates of DJD in older cats, age should be considered a significant risk factor for this disease.

    In retrospective and prospective studies on cats, researchers frequently use the broad term DJD because other causes of apparent osteoarthritis on radiographs cannot be immediately excluded (BOX 1). This means that study results likely include cats with congenital or inherited skeletal disorders (e.g., hip dysplasia, osteochondrodysplasia), secondary changes due to previous infection (e.g., tick-borne diseases), trauma, historical nutritional inadequacies, and low-grade inflammatory or immune-mediated causes. In cases of joint pain, the differential diagnosis should be considered, especially in younger cats, as treatment of an inciting condition (e.g., immune-mediated disease) may be necessary. It has been shown that even young cats can develop DJD and osteoarthritis.2

    Clinical Signs

    Perhaps the most important reason DJD is underdiagnosed in cats is its unique clinical presentation. For physical and behavioral reasons, the prevalent canine medical model of DJD (e.g., lameness, a change in activity level, stiffness, trouble with stairs) cannot be directly applied to cats. The canine medical model includes dogs that will not walk or hike as far as they used to, that tire more easily while playing fetch, that do not leap to their feet when the doorbell rings, and that limp after playing with the dog next door. During physical examination, these patients may appear relaxed until the doctor tries to manipulate the painful joint, which may elicit a yelp, struggle, or growl. Applying this model to cats is problematic because they usually do not go for walks, play fetch, or leap to their feet when someone is at the front door. In addition, cats often do not display classic signs of pain (which may be more true for chronic pain, such as in DJD), and an orthopedic examination may yield few results because of cats’ stoic nature. Also, cats often resist substantial handling at an animal hospital and may be tense, struggling, and growling before joint manipulation; therefore, these behaviors may not be reliable indicators of discomfort.

    Lameness is one of the most common reasons dogs present for orthopedic examinations. Cats show far fewer signs of lameness, possibly because they often have bilateral joint disease2,5 and are generally smaller and more agile than dogs.4 In terms of physical activity, cats tend not to “overdo it” compared with dogs and will stop or curtail a taxing or painful activity before it leads to acute lameness and greater pain. Several studies have suggested that DJD of the elbow may be common in cats,1,5 but subtle gait changes in affected cats may go unnoticed. Studies on DJD in cats detail arthritis of the elbow, hip, stifle, tarsus, and spine, with most cats being affected in more than one area; however, even a cat with arthritis of multiple joints may not appear lame on any one limb.

    Clinical signs of pain in cats are often nonspecific, and clients and veterinary professionals may not interpret behavioral changes as signs of DJD or another disease. Although a behavior change (e.g., no longer jumping onto the bed, struggling to go up stairs) in a dog may immediately raise the suspicion for joint disease, a similar behavior change in a cat may be attributed to the cat’s whim (e.g., “Fluffy is moody,” “Fluffy now prefers to sleep on the couch downstairs”) or may go unnoticed because cats vary their routines more than dogs (e.g., a dog may come to bed at “bedtime” every night; cats may jump on and off the bed at various times during the night).

    Diagnosis

    Osteoarthritis is usually diagnosed by radiographic findings (e.g., the appearance of enthesiophytes, osteophytes, subchondral bone erosion, joint effusion, or periarticular or intraarticular mineralization). Despite these commonly recognized findings, veterinarians’ evaluations of joint disease and its severity may differ because of subjective findings (e.g., the presence of subtle changes, the degree of disease). In reviewing articles on osteoarthritis in cats, the author has found that one of the most prominent issues is the lack of standards in reading radiographs for evidence of DJD and osteoarthritis. However, it is not practical to routinely sedate asymptomatic or nonspecifically symptomatic older or geriatric cats for radiography to detect DJD, so most diagnoses need to be made another way.

    A presumptive diagnosis can be made from a thorough physical examination (including observation of the patient’s carriage, gait, and reaction to handling) and patient history. However, as already discussed, both of these means of diagnosis are problematic with respect to cats. Perhaps the best way to diagnose DJD in cats is to obtain a detailed patient history during each feline examination, asking specific questions to elucidate changes in activity, grooming, and eating habits. Because many clients think certain changes are just part of “growing old,” some of the most common signs of DJD go unreported unless they are expressly questioned (BOX 2). Explicit questions about a feline patient’s at-home behavior should be part of any examination, especially for older cats. Cats generally show nonspecific signs of pain and illness, but behavior changes increase with age.6

    A prospective study in the United Kingdom offered one additional means of diagnosis: treatment with an NSAID.4 Meloxicam therapy for cats with radiographic signs of osteoarthritis (with or without clinical signs) resulted in positive changes in behavior, even in asymptomatic cats. While the decision to use NSAIDs in this species is controversial, this study may support the use of some kind of empirical treatment (including or excluding NSAIDs) for older and geriatric cats. The analgesic-response test is also mentioned in the AAHA/AAFP Pain Management Guidelines for Dogs & Cats: “If a question persists regarding the presence of pain, administer an analgesic and assess the patient’s response.”7

    Treatment

    The treatment of chronic pain and, specifically, DJD should always include lifestyle changes and supportive therapies in addition to prescription drug therapy. Achieving and maintaining a healthy body weight may be, by far, the most important lifestyle change for cats and dogs with, or at risk for, arthritis (risk increases with age or a history of joint surgery or an orthopedic injury or condition). Patients should be as slim as possible while maintaining health and good muscle tone. Activity level and frequency should be determined in consultation with a veterinarian, and the owner should make every effort to keep the cat on a good diet and exercise regimen.

    The multimodal approach to treating chronic pain involves exercise, diet, prescription medications, and nonprescription supplements. Lifestyle and environmental modifications (e.g., facilitating access to food, water, litter, and preferred sleeping areas) may also be recommended for cats showing clinical signs or for geriatric cats in general. Although a comprehensive treatment plan for a patient must be created by the veterinary team, individual treatment options follow.

    Treating Pain and Inflammation

    Treatment of chronic conditions such as osteoarthritis is long-term, and treatments may need to be added, or drug dosages changed, as the disease progresses. The AAHA/AAFP guidelines recommend reassessment of the patient every 3 months7; for practices with many geriatric patients, this can be done through biannual hospital visits (e.g., in January and June) and biannual phone calls or e-mails (e.g., in March and September) from a dedicated technician. In addition, clients should be educated on how to evaluate their cat at home to help ensure the pain remains well controlled.

    The prescription drug treatment options for cats are limited. Research on NSAID therapy for chronic pain in cats is ongoing, but the recent literature describes the use of meloxicam. In the United States, meloxicam’s potential for causing kidney damage resulted in an FDA black-box warning stating that the drug is only for one-time use, making long-term use off label for cats.8 The FDA recently approved robenacoxib, an NSAID for short-term use in cats, but it has only recently become available in the United States. The lack of options for NSAID therapy for feline DJD in the United States is unfortunate because this therapy can be useful for treating chronic pain in cats.a

    Other oral prescription options for DJD-related chronic pain in cats include opioids (e.g., buprenorphine, the synthetic opioid tramadol) and glucocorticoids (e.g., prednisolone, prednisone). In veterinary medicine, opioids have been traditionally used to treat acute and postoperative pain, but these drugs have been used long-term in some cats with DJD because of the difficulty of administering NSAIDs to cats. Long-term use of opioids can have significant adverse effects, such as constipation, and increases the likelihood of diversion (use of a drug by a human family member). Long-term use of opioids can create dependence and require increasing doses to achieve the same effect, though neither of these consequences has been researched in cats. 

    Glucocorticoids (steroids) such as prednisolone can be used for their antiinflammatory effect. They are not analgesics but may provide analgesia through their powerful antiinflammatory action. Systemic steroid use in cats is associated with many adverse effects, the most serious of which may be diabetes mellitus and congestive heart failure; therefore, systemic steroid use cannot be considered a first-line therapy for DJD.

    Amantadine and gabapentin are gaining a foothold for managing chronic pain in dogs and cats. Although detailing the use of these drugs is beyond the scope of this article, they may prove helpful to treating cats with moderate to severe signs of DJD. Neither drug is recommended as a sole therapeutic agent; the two drugs are meant to be part of a multimodal program to address chronic pain.

    Treating the Disease

    All the drugs mentioned above would be prescribed to lessen the clinical signs of DJD. Ideally, treatment of DJD would include drugs that slow the course of the disease; these are called disease-modifying osteoarthritis drugs (DMOADs). The manufacturers of Adequan (polysulfated glycosaminoglycan; Luitpold Pharmaceuticals) and Cartrophen Vet (sodium pentosan polysulfate; Arthropharm Services) report that these injectable DMOADs can be used to treat canine and equine osteoarthritis, and both companies cite research to back these claims. Given intramuscularly in dogs, both drugs target joint cartilage. By keeping the cartilage healthy and intact, further joint destruction is delayed. Both medications are given on a strict schedule: initial, frequent dosing is eventually replaced with once-monthly injections. There is no peer-reviewed research on the use of either drug in cats, but anecdotal reports are promising. Some veterinarians prescribe the drugs for subcutaneous use in cats, allowing owners to administer them at home and avoiding the stress of frequent veterinary visits. Both drugs are heparin analogues, so their use in conjunction with anticoagulants requires veterinary supervision.

    Various oral joint supplements may contain glucosamine, chondroitin, perna mussel, methylsulfonylmethane, hyaluronic acid, and/or avocado and soy unsaponifiables. All these substances claim to lessen joint pain. Most joint supplements claim to improve joint health by strengthening cartilage and decreasing inflammation. For some supplements, there has been a significant amount of research; for others, there has been little or no research. These products are rarely contraindicated, so some veterinarians recommend the animal-specific formulations for use in patients with or at risk of DJD.

    Complementary Treatments

    Various complementary treatments are available for treating chronic joint and muscle pain in cats. Acupuncture, massage, cold laser therapy, and diets containing large amounts of omega-3 fatty acids are among the supportive treatments used to ameliorate the clinical signs of DJD. Some modalities used in dogs (e.g., hydrotherapy, other intensive forms of physiotherapy) are not as suitable for cats because of behavior differences between these species, and any treatment may be limited by a cat’s individual behavior or needs.

    Conclusion

    DJD in cats is progressive and potentially debilitating, and recent evidence shows that a large portion of the population is likely affected. The veterinary team is responsible for identifying and treating DJD to improve the quality of life of cats, particularly as they age. DJD is often diagnosed presumptively through physical examination, laboratory testing to rule out other diseases, and a behavioral history that reveals clinical signs of DJD. Veterinary technicians can play a vital role in the diagnosis by serving as a communication link between the client and the veterinarian. Technicians often obtain a patient’s behavioral history before an examination begins, and questions focusing on potential clinical signs of DJD can be paired with general and specific physical findings (e.g., lack of grooming, overgrown nails) to allow the veterinarian to make a diagnosis.

    Veterinary technicians can also play a role in educating clients. Speaking to clients about the likelihood of cats to develop osteoarthritis allows clients to become better caretakers by giving them the tools to recognize potential signs of pain and discomfort. A cat’s age is no longer an acceptable explanation for muscle wasting, dandruff, and an increasingly “grumpy” demeanor. Clients are more likely to take action if they know that DJD is likely as cats age and that at-home measures can improve their cat’s quality of life. Although cats are traditionally stoic and hardy, they should not have to endure great discomfort. The veterinary team can improve the quality of feline geriatric care by recognizing and managing joint disease.

    aFor a knowledgeable analysis of NSAID therapy for feline chronic pain, see the ISFM and AAFP Consensus Guidelines (2010): “Long-term Use of NSAIDs in Cats.” The IFSM and the AAFP have also published a helpful client handout.

    Downloadable PDF

    1. Hardie EM, Roe SC, Martin FR. Radiographic evidence of degenerative joint disease in geriatric cats: 100 cases (1994–1997). J Am Vet Med Assoc 2002;220(5):628-632.

    2. Lascelles BD, Henry JB 3rd, Brown J, et al. Cross-sectional study of the prevalence of radiographic degenerative joint disease in domesticated cats. Vet Surg 2010;39(5):535-544.

    3. Slingerland LI, Hazewinkel HA, Meij BP, et al. Cross-sectional study of the prevalence and clinical features of osteoarthritis in 100 cats. Vet J 2011;187(3):304-309.

    4. Clarke SP, Bennett D. Feline osteoarthritis: a prospective study of 28 cases. J Small Anim Pract 2006;47(8):439-445.

    5. Godfrey DR. Osteoarthritis in cats: a retrospective radiological study. J Small Anim Pract 2005;46(9):425-429.

    6. Overall KL, Rodan I, Beaver BV, et al. Feline behavior guidelines from the American Association of Feline Practitioners. J Am Vet Med Assoc 2005;227(1):70-84.

    7. AAHA/AAFP Pain Management Guidelines Task Force. Hellyer P, Rodan I, Brunt J, et al. AAHA/AAFP pain management guidelines for dogs & cats. J Am Anim Hosp Assoc 2007;43(5):235-248.

    8. FDA Announces Addition of Boxed Warning to METACAM® (meloxicam) Labels. US Food and Drug Administration. http://www.fda.gov/animalveterinary/newsevents/cvmupdates/ucm231254.htm. Accessed August 21, 2012.

    References »

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    didyouknow

    Did you know... Osteoarthritis commonly occurs in dogs in association with articular diseases such as hip dysplasia, elbow dysplasia, and cranial cruciate ligament rupture.Read More

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