how do I identify and manage iron-restricted erythropoiesis in dogs with chronic inflammatory disease?

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Iron-restricted erythropoiesis (ILE) in dogs with chronic inflammatory disease is identified primarily by reticulocyte hemoglobin content (CHr) and managed by addressing the underlying inflammatory driver alongside iron supplementation when indicated. The mechanism is functional iron deficiency and iron sequestration, not absolute iron depletion. Inflammatory cytokines — including TNF-α, IL-1, IL-6, interferon-α, interferon-β, and interferon-γ — suppress erythropoiesis, while hepcidin (produced as part of the acute phase response, particularly in response to IL-6) causes iron retention and reduces circulating iron availability, blunting the erythropoietic response.6 This means serum iron and ferritin can be misleading: ferritin is a positive acute phase protein and may be elevated into the normal range even when true iron deficiency coexists with inflammation, limiting its diagnostic utility.11 CHr is the primary diagnostic index for ILE in dogs. A CHr below 24.5 pg identifies iron-restricted erythropoiesis, and dogs with IMHA falling below this cutoff have significantly lower hematocrit than those above it.3 On the Sysmex platform, the equivalent index (RET-He) uses a cutoff of less than 20.9 pg — 10.3% of canine CBCs in one large dataset fell below this threshold, and 68.9% of those dogs were anemic.7 Importantly, low RET-He identifies iron-deficient erythropoiesis even when all other CBC variables remain within reference intervals, making it more sensitive than mature red blood cell (RBC) indices for early or subacute ILE.7 Conventional RBC indices — mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) — are late and nonspecific indicators. Given the erythrocyte lifespan of 120 days in dogs, ILE must persist for weeks to months before microcytosis or hypochromasia appear; only 28.9% of anemic dogs with low RET-He in one dataset had concurrent microcytosis and hypochromasia.7 Relying on MCV and MCHC