Comparison of the efficacy of prednisone and cyclosporine for treatment of dogs with primary immune-mediated polyarthritis.

OBJECTIVE: To compare efficacy between cyclosporine and prednisone for treatment of primary immune-mediated polyarthritis (IMPA) in dogs.
DESIGN: Randomized controlled clinical trial. ANIMALS: 20 client-owned dogs with primary IMPA. PROCEDURES: Dogs were randomly assigned to receive prednisone (starting at 1 mg/kg [0.45 mg/lb], PO, q 12 h; n = 10) or cyclosporine (5 mg/kg [2.3 mg/lb], PO, q 12 h; 10) for 90 days. Cyclosporine-treated dogs also received carprofen, tramadol, or both for the first 7 days for analgesia. Data collection, physical examination, and cytologic analysis of synovial fluid samples were performed on days 0, 14, 45, and 90. Trough whole blood cyclosporine concentrations were determined on days 7 to 17 for cyclosporine-treated dogs. Treatment failure was defined as lack of clinical improvement by day 14, lack of cytologic improvement by day 45, or need to change treatment because of adverse effects.
RESULTS: Treatment was successful for 7 prednisone-treated dogs and 7 cyclosporine-treated dogs. Absence of synovial fluid cytologic abnormalities on day 45 was identified for 5 prednisone-treated dogs and 8 cyclosporine-treated dogs. Prednisone-treated dogs were more likely to develop polyuria, polydipsia, and polyphagia than were cyclosporine-treated dogs. Opportunistic infections (ie, demodicosis or Erysipelothrix bacteremia) were identified in 2 cyclosporine-treated dogs and 0 prednisone-treated dogs, and diarrhea developed in 1 cyclosporine-treated dog, requiring treatment discontinuation. CONCLUSIONS AND CLINICAL RELEVANCE: Although the number of dogs evaluated was small, limiting generalizability, results of this study suggested that cyclosporine offers promise as a suitable alternative to prednisone for treatment of IMPA in dogs.