Relationship of hemoglobin concentration to packed cell volume in avian blood samples

To determine whether a proportional relationship exists between hemoglobin (Hgb) concentration and pack cell volume (PCV) in avian blood samples, Hgb concentration measured by a point-of-care portable hemoglobinometer and corresponding PCV were determined in blood samples collected from 128 birds comprising 13 avian orders. For all birds evaluated and pooled across orders, a significant and consistent relationship was found between Hgb concentration and PCV, expressed as Hgb = 0.304 x PCV + 0.461. To determine whether the relationship of PCV and Hgb differs, 9 avian orders with n > or = 8 samples per order were analyzed by linear regression. Individual slopes for the 9 orders did not differ significantly (P = .44), indicating that a single slope can be used to model the avian Hgb to PCV relationship for these taxonomic orders. A single intercept can also be used, with the exception of order Phoenicopteriformes, which was the only intercept that was significantly different from 0 (P = .01). These results indicate that a simplified relationship of Hgb (g/dL) = 0.30 x PCV provides a reasonable estimate of Hgb concentration from the PCV of birds from the orders Anseriformes, Columbiformes, Falconiformes, Galliformes, Passeriformes, Psittaciformes, Sphenisciformes, and Strigiformes, but a separate relationship of Hgb = 0.217 x PCV + 6.69 might be warranted for the order Phoenicopteriformes.