Hematologic and biochemical profiles in Standardbred mares during peripartum

The purposes of this study were to determine physiological changes occurring in hematologic and biochemical parameters in mares between the last month of gestation and the first week after parturition. If a significant change was observed with respect to the reference interval of an adult horse, a further aim of the study was to establish different reference intervals. Blood samples were collected from 62 healthy pregnant Standardbred mares. Seventeen nonpregnant and nonlactating mares were used as a control group. In pregnant mares, blood sampling was conducted every three days from 1 month before the expected foaling date (335 days after the last mating), at parturition, and 7 days after foaling. The barren mares in the control group were sampled once. Results from samples collected 20 and 10 days before parturition, at parturition, and 7 days after were considered in the statistical analysis. A parametric method for all the parameters studied was used to establish reference intervals. Results were compared by repeated measures ANOVA. When significant differences were observed in relation to sampling time, a post hoc analysis was performed (Tukey test). The one-way ANOVA test followed by Dunnett's test was performed to evaluate the presence of a significant difference between each sampling time and the control group. Any significant difference in the blood count parameters at different sampling times was observed by repeated measure ANOVA. Hemoglobin (P < 0.01) and hematocrit (P < 0.01) 7 days after parturition and white blood cell count (P < 0.01) at parturition were significantly different from the control group. Erythrocyte indices and platelet count were within the normal reference intervals as established in the control group. In the biochemical panel, gamma-glutamyltransferase, creatinine, glucose, biliar acids, total protein, albumin-to-globulin ratio, and calcium were significantly different at different sampling times. Moreover, serum concentration of creatine kinase, aspartate aminotransferase, creatinine, blood urea nitrogen, glucose, lactate, total protein, albumin, albumin-to-globulin ratio, calcium, magnesium, sodium, chloride, potassium, and total, direct, and indirect bilirubin was different from that of the control group. Remarkable changes were not observed in alkaline phosphatase, triglyceride, and fibrinogen concentrations. Temporal changes in the hematologic and biochemical parameters observed in the present study in the peripartum and the differences with reference intervals made up for nonpregnant and nonlactating mares could be used to better evaluate the conditions of periparturient mares.