Aplastic anemia in two kittens following a prescription error

A medication error resulted in two kittens being treated with azathioprine (12 and 12.5 mg/kg) instead of azithromycin for 2 weeks. On clinical examination, the kittens were febrile, weak, and had oronasal hemorrhage. Complete blood cell counts indicated severe bone marrow suppression. Treatment consisted of multiple transfusions, antibiotics, and granulocyte colony-stimulating factor. One of the kittens responded to therapy and had a complete recovery. The other kitten was treated for 40 days with no clinical response before dying. Both kittens also contracted Mycoplasma hemofelis infection from a contaminated blood transfusion.