A 7-year-old neutered male Norwegian Forest Cat was presented with decreased appetite and activity,
weight loss,
fever, neutrophilia and hyperglobulinaemia. A physical examination showed painful stifle joints and enlarged popliteal lymph nodes. Blood examination showed neutrophilia, hyperglobulinaemia and increased
serum amyloid A. Urinalysis, thoracic and abdominal radiographs, and abdominal ultrasonography were unremarkable. Synovial fluid from the knee joints had diminished viscosity and revealed neutrophilic
inflammation on the smear. There was no evidence of
infection in a microbiological culture of the synovial fluid. A diagnosis of idiopathic immune-mediated
polyarthritis (
IMPA) was made.
Prednisolone was initiated at 2 mg/kg q24h PO and tapered with additional
immunosuppressants (
leflunomide,
ciclosporin A and
methotrexate); however,
prednisolone could not be discontinued. Informed consent was obtained from the owner and
mycophenolate mofetil (MMF) at a dosage of 10 mg/kg q12h PO was initiated on day 798. There were no adverse effects of MMF and
prednisolone was discontinued on day 1183. Clinical signs resolved and the cat's general condition remained stable with MMF alone at a dosage of 10 mg/kg q48h PO on day 1600.
RELEVANCE AND NOVEL INFORMATION: There is limited information describing feline
IMPA and its treatment options other than the use of
prednisolone. This is the first report of the successful treatment and long-term follow-up of feline
IMPA with MMF. MMF may be a safe and effective option as an additional
immunosuppressant in feline
IMPA.