In a senior dog with non-regenerative anemia, which two major differential diagnoses should be considered?

• A. Anemia of chronic disease (inflammation/CKD) and iron deficiency
• B. Iron poisoning
• C. Acute blood loss
• D. Polycythemia

Answer: (A)

Non-regenerative anemia in an older dog points to conditions that chronically impair red blood cell production or iron availability rather than an acute loss or rapid destruction. The two major differential diagnoses to consider are anemia of chronic disease (inflammation or kidney disease) and iron deficiency.

Anemia of chronic disease arises with ongoing inflammation or reduced kidney function. Inflammation triggers cytokines that keep iron locked away in stores and blunt the bone marrow’s response to erythropoietin, so production of new red blood cells slows. In CKD specifically, decreased erythropoietin production adds to the problem. The typical pattern is a normocytic, normochromic non-regenerative picture early on, with low serum iron and iron being less available despite adequate or increased stores, and ferritin that may be normal or elevated due to the inflammatory state.

Iron deficiency results from chronic blood loss or malabsorption, gradually depleting iron stores needed for hemoglobin synthesis. This often leads to microcytosis and hypochromia as the deficiency progresses. Lab findings usually show low iron and low ferritin (though ferritin can be affected by inflammation), with changes in transferrin/total iron-binding capacity reflecting diminished iron availability.

Iron poisoning, acute blood loss, and polycythemia don’t fit as primary chronic non-regenerative etiologies in this context. Iron poisoning is an acute toxic process; acute blood loss is typically regenerative after the initial lag unless ongoing bleeding persists; polycythemia is an elevation of red cells, not a non-regenerative anemia.