A Glance at Anemia in Cats

Cats tend to be prone to anemia because of their low blood volume and the short life-span of the feline RBC (70 days). Compensatory mechanisms enable anemia toleration in chronic conditions, with signs apparent mostly in acute cases. 

Nonregenerative anemia tends to be chronic, usually caused by primary bone marrow disorders or systemic bone marrow suppression. Anemia of inflammatory disease and chronic kidney disease (CKD) are common causes of chronic anemia. Pure red cell aplasia is caused by selective erythroid bone marrow depletion. Less common are myeloproliferative disorders or myelophthisis. Regenerative anemia from blood loss is common (especially after trauma), as is hemolysis. Aggregate (as opposed to punctate) reticulocytes reflect active regeneration; a rising reticulocyte count may not be evident for 3–5 days and peaks at 5–7 days. PCV may take 2–3 weeks to normalize after bleeding. 

Signs (eg, pallor, weakness, jaundice, fever, pica, tachycardia, heart murmur, tachypnea, splenomegaly, hepatomegaly) are largely based on anemia severity, commonly classified as mild, moderate, severe, or very severe (PCV <10%). Nonregenerative anemia is characterized by minimal anisocytosis, polychromasia, and low reticulocyte count with normocytic/normo-chromic erythrocytes. Treatment includes addressing primary or secondary disorder, blood transfusions as needed, and oxygen supplementation for cats with acute signs.

Commentary

In humans, chronic anemia can lead to fatigue, nausea, dizziness, and weakness, suggesting that these signs may be true for cats. This may be especially important in CKD cases, where up to 40% of cats with end-stage disease may be anemic. Careful attention to diet, husbandry, and clinical changes (eg, poor hair coat, pallor, weakness) must be paid when determining if anemia treatment is warranted. Although vitamin or iron therapy has not been shown to improve chronic anemia in certain disease states, benign supplementation may help improve some aspects of quality of life.—Heather Troyer, DVM, DABVP, CVA