Anaplasmosis in cattle is an infectious disease of the red blood cells caused by the rickettsial bacteria Anaplasma marginale. Most commonly transmitted by ticks, A. marginale primarily causes disease in cattle. Other domestic and wild ruminants such as bison, deer, elk, sheep and goats can be infected, but clinical disease is uncommon.

Anaplasmosis is a provincially notifiable disease for cattle and yaks, sheep and goats, domestic cervids and wild cervids, farmed bison and wild bison, and ruminant animals residing in a zoo.