Case reportA male Domestic Short-hair cat was presented for chronic weight loss, lethargy and hyporexia. Complete haematological examination revealed non-regenerative anaemia, neutropenia and thrombocytopenia, as well as Howell-Jolly bodies, anisocytosis, polychromasia and macrocytosis on blood smear evaluation. Histopathological evaluation of bone marrow biopsy disclosed hypocellularity consistent with bone marrow failure. Concurrent hypocobalaminaemia was identified and treated with parenteral cyanocobalamin supplementation. Other differential diagnoses for pancytopenia, including infectious, toxic, immune-mediated and neoplastic causes, were ruled out. ConclusionThe cat's erythrocyte, leucocyte and platelet counts normalised after 2months of cyanocobalamin supplementation, suggesting that pancytopenia may be a rare manifestation of feline cobalamin deficiency.