Osteoarthritis in cats: What we now know about recognition and treatment - Veterinary Medicine
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Osteoarthritis in cats: What we now know about recognition and treatment
An unkempt appearance. Hesitancy to jump onto a cozy spot. Even though many senior cats have radiographic evidence of degeneration, the signs of this painful condition can be subtle. Here's what to look for and how to alleviate cats' suffering.


VETERINARY MEDICINE


As with dogs, monitor cats receiving NSAIDs for chronic pain for side effects related to renal and hepatic function and gastrointestinal erosions. No monitoring guidelines have been established, but a serum chemistry profile, packed cell volume, and total protein measurement are recommended before you initiate treatment and should be repeated at one and four weeks. After this, the timing of follow-up blood work is arbitrary and will vary in each patient. As with dogs, it is important to discuss the possible side effects of these drugs with the owner, and if vomiting or anorexia occurs, the client should stop administration and seek veterinary advice. It is also imperative to inform the owner that under no circumstances should any over-the-counter anti-inflammatory drugs such as aspirin be given in conjunction with an NSAID. Continual reassessment of the patient both by the veterinarian and owner is important so that the dose can be tapered to the smallest effective amount.

Opioids. In my experience, because of their side effects such as euphoria, inappetence, and constipation after long-term use (days or weeks), opioids are best reserved for terminal or hospice care in cats or for occasional breakthrough pain while the cat is receiving other analgesics or undergoing other treatment modalities.

Other analgesic drugs. The role of other drugs in alleviating chronic osteoarthritis-related pain has not been well-studied in cats. Several drugs have, however, been suggested.

Tricyclic antidepressants including amitriptyline, clomipramine, and imipramine can provide relief in people with chronic neuropathic pain and are thought to alter the actions of serotonin and norepinephrine both centrally and peripherally.13 Anecdotal reports suggest that amitriptyline (between 2.5 and 12.5 mg for an adult cat orally once a day) may be effective for chronic pain syndromes in cats including osteoarthritis.

The anticonvulsant gabapentin is clinically effective in relieving some types of chronic pain in people, although the mechanism of action is not clear.14 Individual case reports demonstrate that gabapentin shows promise in cats,15 and doses starting at 10 mg/kg given orally twice a day have been suggested.16 Some animals become sedate and occasionally ataxic when given gabapentin. These signs may decrease as a cat acclimates to the drug or can be managed by decreasing the dose. In my experience, the tablet and capsule formulations of gabapentin are more palatable and easier to administer to cats than the liquid oral formulation, and they don't contain xylitol.

Although not classified as an opioid, tramadol has weak binding affinity at mu-receptors. It is thought to activate monoaminergic spinal inhibition of pain, although this may not apply to nonprimate species. It can be administered by multiple routes, including orally, is effective for relieving moderately severe acute and chronic pain in people, and seems remarkably devoid of the usual undesirable side effects of opioids such as respiratory depression and tolerance.17 The pharmacokinetics of tramadol and its major metabolite has recently been reported in cats18 ; doses in cats would likely be less than those in dogs (on a mg/kg basis) and the dosing interval may be longer. As of yet, no published studies have reported tramadol's efficacy for relieving osteoarthritis pain in cats. The chief problem with tramadol is its bitter and unpleasant taste, which makes administering it to cats difficult, even after compounding with fish or chicken flavors.

Nonpharmacologic intervention

Rehabilitation therapy (underwater treadmill, passive range of motion, creative exercise techniques), nutraceuticals (e.g. chondroitin sulfate), and acupuncture are also used to treat osteoarthritis in cats with varying success. Many cats are more tolerant of these interventions than you might think.

Editors' note: Dr. Robertson has received financial support from Boehringer-Ingelheim Vetmedica to conduct workshops for Boehringer-Ingelheim veterinarians, write one review article, and speak at veterinary continuing education meetings.

Sheilah A. Robertson, BVMS (Hons), PhD, DACVA, DECVA, CVA, MRCVS
Section of Anesthesia and Pain Management
College of Veterinary Medicine
University of Florida
Gainesville, FL 32610

REFERENCES

1. Clarke SP, Mellor D, Clements DN, et al. Prevalence of radiographic signs of degenerative joint disease in a hospital population of cats. Vet Rec 2005;157(25):793-799.

2. 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.

3. Gordon WJ, Conzemius MG, Riedesel E, et al. The relationship between limb function and radiographic osteoarthrosis in dogs with stifle osteoarthrosis. Vet Surg 2003;32(5):451-454.

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

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6. Lascelles BD, Hansen BD, Thomson A, et al. Evaluation of a digitally integrated accelerometer-based activity monitor for the measurement of activity in cats. Vet Anaesth Analg 2008;35(2):173-183.

7. Lascelles BD, Hansen BD, Roe S, et al. Evaluation of client-specific outcome measures and activity monitoring to measure pain relief in cats with osteoarthritis. J Vet Intern Med 2007;21(3):410-416.

8. Runk A, Kyles AE, Downs MO. Duodenal perforation in a cat following the administration of nonsteroidal anti-inflammatory medication. J Am Anim Hosp Assoc 1999;35(1):52-55.

9. Taylor PM, Delatour P, Landoni FM, et al. Pharmacodynamics and enantioselective pharmacokinetics of carprofen in the cat. Res Vet Sci 1996;60(2):144-151.

10. Parton K, Balmer TV, Boyle J, et al. The pharmacokinetics and effects of intravenously administered carprofen and salicylate on gastrointestinal mucosa and selected biochemical measurements in healthy cats. J Vet Pharmacol Ther 2000;23(2):73-79.

11. Lascelles BD, Henderson AJ, Hackett IJ. Evaluation of the clinical efficacy of meloxicam in cats with painful locomotor disorders. J Small Anim Pract 2001;42(12):587-593.

12. Gunew MN, Menrath VH, Marshall RD. Long-term safety, efficacy and palatability of oral meloxicam at 0.01-0.03 mg/kg for treatment of osteoarthritic pain in cats. J Feline Med Surg 2008;10(3):235-241.

13. Sawynok J. Topical and peripherally acting analgesics. Pharmacol Rev 2003;55(1):1-20.

14. Morello CM, Leckband SG, Stoner CP, et al. Randomized double-blind study comparing the efficacy of gabapentin with amitriptyline on diabetic peripheral neuropathy pain. Arch Intern Med 1999;159(16):1931-1937.

15. Lamont LA, Tranquilli WJ, Mathews KA. Adjunctive analgesic therapy. Vet Clin North Am Small Anim Pract 2000;30(4):805-813,vii.

16. Gaynor JS. Other drugs used to treat pain. In: Gaynor JS, Muir WW, eds. Handbook of veterinary pain management. St. Louis, Mo: Mosby, 2002;251-260.

17. Lee CR, McTavish D, Sorkin EM. Tramadol. A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in acute and chronic pain states. Drugs 1993;46(2):313-340.

18. Pypendop BH, Ilkiw JE. Pharmacokinetics of tramadol, and its metabolite O-desmethyl-tramadol, in cats. J Vet Pharmacol Ther 2008;31(1):52-59.


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