Acanthocytes or spur cells, are spherical cells with blunt-tipped or club-shaped spicules of different lengths projecting from their surface at irregular intervals. (Echinocytes, or crenated red cells, in contrast, have shorter, sharp to blunt spicules of uniform length which are more evenly spaced around their periphery).       These cells are seen most commonly as a major morphologic feature in dogs with hemangiosarcoma (often accompanied by regenerative anemia). The mechanism of their formation is unknown in this disease (and is probably related to fragmentation), but their presence in the right context (regenerative anemia and thrombocytopenia) is a definite signal to look for other evidence of this condition.       Acanthocytes also can be seen in some dogs and cats with liver disease (± anemia), and dogs with iron deficiency, renal disease and microangiopathic hemolytic anemias (fragmentation), e.g. DIC.