Causative agent: Dermacentor andersoni
Ticks are common vectors of disease. They are bloodsuckers and can cause anemia and reduced growth rates. Some ticks are able to produce a neurotoxin that causes paralysis. Tick paralysis has been reported from bison in Montana (57).
Clinical signs:
The clinical signs of tick infestation in bison are associated with tick paralysis. Initially, infested bison have an unsteady gate, and jerky movements. The animals lie down and then are unable to get up. Tick paralysis was only seen in bison calves and yearlings (57).
Diagnosis:
The ticks are easily observed on the skin of the bison.
Treatment:
Remove the ticks from the bison. There are a number of products that may be used for treating infested cattle . Many of them work well, but most do not have residual effect. Products that have been used in cattle include avermectins, organophosphates, and pyrethroids. Sprays and dips are commonly used to treat cattle with ticks.
Control:
Ticks are difficult to control. Rotating pastures, and frequent treatment may reduce the level of ticks on the pasture and on bison, but complete eradication is unlikely.