Sudden Mortality in Captive White-Tailed Deer with Atypical Infestation of Winter Tick

In October 2020, three captive male white-tailed deer, Odocoileus virginianus [Zimmermann] (artiodactyla: Cervidae), were found dead in central Pennsylvania and a fourth was euthanized due to extreme lethargy. The deer presented with high burdens of Dermacentor albipictus (Packard) (Ixoda: Ixodidae) (winter tick). There were no other clinical symptoms and deer were in otherwise good physical condition with no observed alopecia. Winter tick epizootics have been associated with mortalities of moose, Alces alces [Linnaeus] (artiodactyla: cervidae), and more recently elk, Cervus canadensis [Erxleben] (artiodactyla: cervidae), in Pennsylvania, but have not been reported in white-tailed deer. Mild winters are favorable to winter ticks and deer producers and managers should be aware of possible infestations as a result.