Immune-Mediated Erythroid Hypoplasia and Anemia in an African Clawless Otter (Aonyx capensis)
An estimated 9-year-old adult male African clawless otter (Aonyx capensis) presented with acute lethargy, ataxia, and tachypnea. A full diagnostic examination revealed severe, regenerative anemia (PCV 9%), elevated prothrombin time (35.6 sec), hypoproteinemia (TS 4.0 mg/dl), and an elevated blood urea nitrogen (59 mg/dl). Radiographs, abdominal ultrasound, abdominocentesis, and upper gastrointestinal endoscopy failed to identify the source of the anemia. Five days later, when the anemia had not improved, the animal was transfused with Oxyglobin® (250 ml), a bone marrow aspirate and biopsy were collected, and prednisone therapy (1.06 mg/kg PO SID) was initiated. The bone marrow aspirate confirmed erythroid hypoplasia associated with erythrophagocytosis, consistent with a consumptive process, likely due to an immune-mediated and/or infectious process.
Infectious disease testing for dirofilariasis, borreliosis, and ehrlichiosis was negative, and the animal was continued on the prednisone for 9 months while the PCV gradually increased to a high of 54%. By that time, the animal had developed a thinning hair coat, presumably due to induced hyperadrenocorticism. The otter was tapered off the steroids over 3 months, the presumed hyperadrenocorticism resolved, and the animal is currently in remission.
The authors would like to thank the veterinary staff, curators, and keepers of the Toledo Zoo for their assistance in the care and management of the otter in this report.