When evaluating anemia in an elderly dog, which two major etiologies should be considered?

• A. Anemia of CKD (non-regenerative) and iron-deficiency anemia from chronic GI blood loss or malabsorption
• B. Polycythemia
• C. Acute blood loss anemia
• D. Immune-mediated thrombocytopenia

Answer: (A)

In elderly dogs, anemia is most often driven by chronic diseases that blunt red blood cell production or iron supply. The two main etiologies to consider are anemia associated with chronic kidney disease and iron-deficiency anemia from ongoing GI blood loss or problems absorbing iron.

Kidney disease reduces the kidney’s production of erythropoietin, a hormone that signals the bone marrow to make red cells. Without adequate erythropoietin, red cell production is diminished, leading to a non-regenerative form of anemia. You’d typically see a lower reticulocyte count and a relatively steady, but reduced, hemoglobin level as kidney function declines.

Iron deficiency stems from chronic GI blood loss (from ulcers, neoplasia, or similar issues) or malabsorption that prevents iron from being available for hemoglobin synthesis. This causes a supply shortage for making new red cells, often producing microcytosis (smaller red cells) and hypochromasia (paler red cells) with a low reticulocyte response.

Other potential causes—such as acute blood loss, immune-mediated destruction, or platelet disorders—can produce anemia but are less characteristic as the dominant etiologies in an elderly patient presenting with a chronic, non-regenerative pattern. The key is recognizing the two common, age-associated pathways: reduced red cell production from kidney failure and iron-restricted erythropoiesis from chronic GI loss or malabsorption, and then evaluating with renal function tests, urinalysis, and iron studies to guide diagnosis and treatment.