Disseminated Mycobacterium avium complex infection following renal transplantation in a cat

A n 11-year-old 3.9-kg (8.6 lb) spayed female domestic shorthair cat with a history of chronic renal failure and renal transplantation 18 months previously was referred to the Veterinary Hospital of the University of Pennsylvania because of a 2-month history of progressive lethargy, weight loss (0.68 kg [1.5 lb]), decreased appetite, vomiting, diarrhea, and hematochezia.There was no recent history of polyuria, polydipsia, coughing, or sneezing.The cat was being treated with cyclosporine a (3.5 to 8 mg/kg [1.6 to 3.6 mg/lb], PO, q 12 h).The mean blood cyclosporine concentration, determined by means of high-performance liquid chromatography, was 401 ng/mL (target range, 300 to 500 ng/mL) during the first 6 months after transplantation and 206 ng/mL (target range, 200 to 300 ng/mL) during the subsequent 12 months.The cat had received prednisolone at a gradually decreasing dosage (initially, 1.5 mg/kg [0.7 mg/lb], PO, q 12 h) for the first 8 months after transplantation.In the 10 days prior to examination at the University of Pennsylvania, the cat had received two 5-day courses of antimicrobials for treatment of a possible bacterial infection.Physical examination revealed signs of mild depression and an unkempt coat.The body condition score was 4 on a scale from 1 to 9. Rectal temperature was slightly elevated (39.7 o C [103.5 o F]), and a grade II of V systolic cardiac murmur could be auscultated.The abdomen was not deeply palpated, as this could cause avulsion of the renal allograft from its attachment to the renal artery and vein. Diagnostic procedures performed on admission included a CBC; serum biochemical panel; urinalysis; bacterial culture of a urine sample; measurement of serum total thyroxine (T 4 ) concentration; assays