The common domestic equine species present various hematological differences within reference values as a result of age, breed, sex, physical activity, among others. Therefore, it is important that reference intervals should be established for these particularities. This work aimed to evaluate sequential changes in hematological parameters of healthy Thoroughbred foals from birth to six months of life. Blood samples were collected immediately after birth (before the intake of colostrum), at 24 h, 7 days, 1, 2, 3, 4, 5 and 6 months of age in order to measure packed cell volume (PCV), total plasma protein (TPP), fibrinogen and white blood cells (WBC). Descriptive statistics, analysis of one-way AOV and comparison between means by LSD test were accomplished. Hematological values were assessed in 1426 samples. The curve variations in PCV, total plasma protein, fibrinogen and WBC values observed in healthy Thoroughbred foals from birth to 6 months were similar to those described for other breeds. However, we verified higher TPP values than mean reference values at all ages. The ranges of fibrinogen and WBC showed small intervals and maximum values below the hematologic reference values for all ages. These changes in hematologic values provide useful information for clinical evaluation of Thoroughbred foals.
equine neonatal; fibrinogen; hematologic profile; total plasma protein