Presumptive fenbendazole toxicosis in North American porcupines

Case Description - 4 North American porcupines were evaluated because of diarrhea or neutropenia (or both) that developed after treatment with fenbendazole for intestinal parasites. Clinical Findings - Complete blood cell count abnormalities included severe neutropenia in all affected porcupines and mild anemia in some of them. In 2 porcupines, postmortem findings included bone marrow hypoplasia and intestinal crypt cell necrosis. Treatment and Outcome - Affected porcupines received supportive care including fluid supplementation and broad-spectrum antimicrobials. The 2 surviving animals recovered after 9 to 33 days of treatment. Conclusions and Clinical Relevance - Fenbendazole is an anthelminthic that may be used in an extralabel manner for the treatment of intestinal parasitism in wildlife species. The drug inhibits mitosis and can affect rapidly dividing cell lines, such as those in the bone marrow and intestinal crypt mucosa. Fenbendazole may not be an appropriate anthelminthic choice in North American porcupines.