Biliary Coccidiosis Associated With Immunosuppressive Treatment of Pure Red Cell Aplasia in an Adult Ferret (Mustela putorius furo)

An 18-month-old female spayed ferret was diagnosed with severe anemia secondary to pure red cell aplasia (PRCA). After 3 months of immunosuppressive therapy for PRCA, the patient presented with anorexia, melena, and jaundice. A biochemical profile showed elevated hepatobiliary enzymes and a marked hyperbilirubinemia suggestive of cholestatic disease. Despite aggressive supportive care, the patient's clinical status worsened and euthanasia was elected. The most significant necropsy findings were chronic proliferative cholecystitis and choledochitis with intraepithelial coccidian parasites. Diagnostic analysis of a fragment of the parasite's small subunit ribosomal RNA gene using polymerase chain reaction amplification and DNA sequencing revealed 100% sequence identity to that of Eimeria furonis. The authors believe immunosuppressive therapy for PRCA predisposed this ferret to an opportunistic parasitic infection; clinicians managing PRCA should be aware of this potential complication. To reduce the likelihood of clinical disease associated with Eimeria spp. infections, coccidiostats should be considered as an adjunct treatment for ferrets on long-term immunosuppressive therapy.