Reference intervals for haematological parameters in the Lusitano horse breed

The Lusitano horse is an autochthonous Portuguese breed with a growing worldwide expansion. Our objective was to establish reference intervals for haematological parameters using the haematological cell counter LaserCyte (IDEXX). For this purpose, blood samples from 100 healthy adult horses (13 females and 87 males, ranging from 3 to 25 years of age) were analysed. The reference intervals were estimated following the ASVCP guidelines with the Reference Value Advisor software. The obtained reference intervals were 6.4-10.1 × 10¹²/L for red blood cells, 30.6-45.1% for haematocrit, 11.6-17.1 g/dL for haemoglobin, 42.8-53.2 fL for mean corpuscular volume (MCV), 15.5-20.8 pg for mean corpuscular haemoglobin (MCH), 33.7-39.4 g/dL for mean corpuscular haemoglobin concentration, 17.8-20.3% for red cell distribution width (RDW), 4.5-10.1 × 10⁹/L for white blood cells, 2.2-6.0 × 10⁹/L for neutrophils, 0.9-4.9 × 10⁹/L for lymphocytes, 0.2-0.5 × 10⁹/L for monocytes, 0.1-0.6 × 10⁹/L for eosinophils, 0.0-0.1 × 10⁹/L for basophils, 78.5-172.2 K/mL for platelets, 4.3-9.4 fL for mean platelet volume, 18.8-24.2% for platelet distribution width, and 0.06-0.12% for plateletcrit. LaserCyte equine reference intervals are transferable to the Lusitano horse for 18 of the 22 analytes studied. Regarding age, significant statistical differences were observed for MCV, RDW, neutrophils and lymphocytes between the mean values of young (3-6 years old), middle-aged (7-14 years old) and old (< 15 years old) age groups. MCH means were statistically significantly different between the three age groups. The haematological reference intervals established in this study might represent a valuable and applicable tool for haematological assessment of adult Lusitano horses, providing useful information that helps clinicians to interpret clinical data.