Babesiosis

RBC destruction and anemia caused by Babesia spp. of intracellular protozoa
B. cani—a large (4–7 mm-long), pear-shaped parasite of canine RBCs; in the U.S., strains generally cause mild or inapparent disease in adults (unless immunosuppressed), but severe disease in pups; South African strains cause severe disease and death in some adult dogs.
B. gibsoni—a small (2.5 mm), ring-shaped organism that causes severe disease in most infected adult dogs; rare in the U.S. but common in Africa and Asia; organisms can be difficult to see in stained blood films.
B. felis—a very small (1 mm), ring-shaped organism that occurs in cats in Africa and southern Asia; of similar size and morphology to Cytauxzoon felis, which occurs in cats in the U.S.