Evaluation of erythrocyte morphology and prevalence of poikilocytes in peripheral blood of sick domestic ferrets (Mustela putorius furo)

To evaluate the prevalence of poikilocytes on peripheral blood smears of sick domestic ferrets and to determine if any erythrocyte morphologic anomalies are associated with a specific diagnosis. Peripheral blood smears from ferrets that presented to the Centre Hospitalier Universitaire Vétérinaire between August 2010 and January 2015. Red blood cell morphologic changes were scored by each reviewer and the presence of keratocytes, acanthocytes, schizocytes, and codocytes was compared to the final diagnosis assigned to each patient, as determined by evaluation of their medical records. A total of 83 ferrets met the inclusion criteria. Clinical diagnoses included adrenal disease (n = 27), lymphoma (n = 14), insulinoma (n = 5), gastrointestinal disease (n = 25), liver disease (n = 9), and other (n = 22). No ferrets had eccentrocytes or basophilic stippling and the most frequently observed red blood cells morphologies were echinocytes (86.7%), polychromatophils (66.2%), and Howell-Jolly bodies (14.4%). The presence of poikilocytes that are often considered to be of pathologic significance was noted 12 times in 9 ferrets: schizocytes (n = 7), codocytes (n = 3), acanthocytes (n = 1), and keratocytes (n = 1). Significantly higher numbers of acanthocytes and schizocytes were observed in ferrets with lymphoma. However, schizocytes were also observed with gastrointestinal disease. The results suggest that ferrets with lymphoma may be more likely to have schizocytes and acanthocytes in their peripheral blood. However, the sensitivity and specificity of these changes need to be more comprehensively evaluated. Studies using larger numbers of ferrets with lymphoma and gastrointestinal diseases and studies evaluating blood smear abnormalities in healthy ferrets are warranted.