Characterisation of the Haematological Profile in the Posavje Horse Breed.

The aim of this study was to investigate the influences of sex and age on haematological values in the Posavje Horse breed. A total of 163 healthy Posavje horses (30 foals, 94 mares and 39 stallions) were used in this study; their complete blood counts and a leucogram were obtained with a haematological analyser. The horses were classified into five groups: foals (1 to 6 months, n = 30), 3 to 6 years (n = 8 stallions/21 mares), 7 to 9 years (n = 9 stallions/22 mares), 10 to 13 years (n = 8 stallions/20 mares), 14 to 15 years (n = 6 stallions/10 mares) and 16 and over (n = 8 stallions/21 mares). The results obtained show an influence of sex on haematological parameters, with red blood cell count (RBC), haematocrit (HCT) and haemoglobin concentration (HGB) being higher in stallions (P < 0.001) and white blood cell count (WBC) being higher in mares. Differences between the age groups of the Posavje horses examined indicate a decrease in RBC and HGB with a compensatory increase in mean corpuscular volume and mean corpuscular haemoglobin, a decrease in WBC and platelet counts (PLT) and proportion of lymphocytes, and an increase of neutrophil to lymphocyte ratio (N/L) with age (P < 0.001). Although the Posavje horse is classified as a draft horse breed, its haematological parameters show characteristics common to warm-blooded breeds, with the exception of the N/L ratio. One of the most important findings of this study is a higher neutrophil count in reproductively active breeding stallions. Higher levels of RBC, HGB, HCT and neutrophil count in the Posavje stallions suggest an effect of androgens (testosterone), which may be an effective mechanism to prevent infections, that can affect the survival of the stallions and thus the evolution of the species. [ABSTRACT FROM AUTHOR]