Neutrophils have distinct pink granules, while eosinophils have round granules like dogs. Lymphocytes can outnumber neutrophils in healthy cattle, and are more variable in size than other species (many cattle have intermediate lymphocytes in blood). There is nothing unique about monocytes, which are still the largest cell in blood. Basophils have prominent purple granules (arrows, lower left panel), but are seen infrequently in sick or healthy cattle. Bovine red blood cells are similar to cats and horses with regard to size and degree of anisocytosis but they are resistant to rouleaux formation. The latter characteristic is the reason that cow blood is very slow to settle out on standing. Bovine red blood cells have a small area of or no central pallor. Platelets in ruminant blood are small, moderately variable in size, and distinctly granulated (arrows, lower right panel). Ruminants usually have higher platelet counts than dogs, cats or horses.
