Efficacy of Fenbendazole against Gastrointestinal Nematodes in White-Tailed Deer

Abstract

We provided fenbendazole to captive (N = 77) and free-ranging (3 study areas) white-tailed deer (Odocoileus virginianus) in Louisiana to determine effects on gastrointestinal nematode burdens. Fenbendazole reduced gastrointestinal nematode burdens of captive and free-ranging white-tailed deer. Mean eggs per gram of feces from captive deer decreased (P < 0.01 and P < 0 .01, respectively) 89% and 84% after provision of fenbendazole in doses approximating 0.47 and 0.62 g/deer, respectively. Doses approximating 0.42-0.46 g/deer did not affect (P = 0.61) eggs per gram of feces collected from free-ranging deer. Mean eggs per gram of feces collected from free-ranging deer was affected by fenbendazole treatment (P = 0.04) and decreased an average of 86% (SE = 1.9) on the 3 study areas after provision of fenbendazole in doses approximating 1.67-1.82 g/deer. Eggs per gram of feces collected from the distal colon and abomasal parasite counts from abomasa of free-ranging deer harvested on the study areas were associated positively (r = 0.706, P < 0 .001), were affected by fenbendazole treatment (P < 0.01 and P < 0 .01, respectively), and decreased 66% (SE = 5.1) and 52% (SE = 7.4), respectively, after provision of fenbendazole in doses approximating 1.67-1.82 g/deer. A reduction in the crosstransmission of gastrointestinal parasites common to deer and livestock might be possible through fenbendazole treatment of deer.