Microcytic hypochromic iron deficiency anaemia in dogs
10-year-old German Shepherd with progressive lethargy and intermittent black faeces for two months. Very pale mucous membranes.
| Parameter | Result | Reference |
|---|---|---|
| Haematocrit | 21% | 37–55 |
| MCV | 54 fL | 60–77 |
| MCHC | 29 g/dL | 32–36 |
| Reticulocytes | 75,000/µL | < 60,000 |
| Platelets | 720,000/µL | 200,000–500,000 |
| Blood smear | Hypochromia, keratocytes, schistocytes | — |
What is the most likely cause of the anaemia?
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A. Anaemia of inflammatory disease
It is usually mild to moderate, normocytic and normochromic. Such marked microcytosis with hypochromia indicates a true lack of iron, not just sequestered iron.
B. Portosystemic shunt
It causes microcytosis, but with mild or no anaemia and no marked hypochromia, and is usually seen in young dogs. It does not explain the melaena or severe anaemia.
C. Immune-mediated haemolytic anaemia
IMHA is typically strongly regenerative, often macrocytic, with spherocytes or agglutination. Here regeneration is poor and the pattern is microcytic.
D. Iron deficiency due to chronic gastrointestinal blood loss
Correct. Hypochromic microcytosis, poor regeneration, thrombocytosis and red cell fragmentation (keratocytes, schistocytes) are typical of iron deficiency. Melaena points to gastrointestinal ulceration or neoplasia.
lightbulb Key takeaway
In adult dogs, iron deficiency means chronic external blood loss until proven otherwise: gastrointestinal, heavy flea burdens or hookworms in puppies. Find the source; supplementing iron without locating the bleeding does not solve the problem.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.