INTERNAL GROSS PATHOLOGY OF MOOSE EXPERIMENTALLY INFESTED WITH WINTER TICKS

Abstract

Captive moose (Alces alces) infested with 21,000 and 42,000 larval winter ticks (Dermacentor albipictus) in September-October, and unifested moose were studied to assess impact of winter ticks on moose. Study animals were euthanized the following April near the end of the parasitic phase of winter ticks. Major organs and selected superficial lymph nodes were examined and compared among treatment groups. No visible lesions were evident in spleen, lung, liver, thyroid, heart, adrenal, and kidney of most moose. Several foci of necrosis in the liver of 1 moose were considered minor and unrelated to tick infestation. Prescapular and prefemoral lymph nodes, but not popliteal nodes, were significantly heavier and reddened in infested than uninfested moose. Hyperactive, hypertrophied lymph nodes may compromise the immune defense of moose and may predispose infested moose to increased risk of bacterial infection. While not a proximate cause of death in heavily infested moose, bacterial infections may contribute as a secondary cause of death.