Romiplostim Use in Pancytopenia Secondary to Azathioprine Overdose in a Dog

A 4 yr old spayed female Kerry blue terrier was presented for pancytopenia secondary to an azathioprine overdose at a referral hospital. The dog was initially prescribed prednisone at 1 mg/kg q 24 hr and azathioprine at 1.6 mg/kg q 24 hr for immune-mediated polyarthropathy. Over 12 wk, the doses were tapered following clinical remission of immune-mediated polyarthropathy. For an unknown period, owner dosing error suggested a drug overdose of azathioprine at 4.8 mg/kg every other day instead of the prescribed 1.6 mg/kg every other day dose. The drugs were discontinued, and the dog presented for bone marrow failure and associated pancytopenia. Romiplostim was administered at 5 μg/kg subcutaneously on three time points (upon initial presentation to the referral facility, day 8 after initial presentation, and day 15 after initial presentation). Repeat bloodwork at the different time points revealed improvement of the pancytopenia. Romiplostim has been used exclusively for thrombocytopenia in dogs; however, literature in humans and mice models suggests that it can influence multiple cell lines. This case report suggests that romiplostim administration can be considered in cases of pancytopenia and may accelerate bone marrow recovery.