Changes in Neonatal Foal Blood Chemistry during the First 72 Hours of Life

Limited research has been conducted to determine normal blood chemistry in equine neonates because the majority of data is derived from case studies of unhealthy foals. The objective of this study was to determine blood chemistry changes during the first 72 h of life in foals. Quarter horse foals (n = 6; 2 primiparous dams and 4 multiparous dams) were monitored closely at foaling. Time of parturition was recorded and jugular blood samples were collected from foals pre-suckling (within 85 min of parturition) and at 6, 12, 24, 48, and 72 h from initial sampling. Serum was used to determine blood chemistry within 48 h of sampling (Equine Maxi Chem Panel, MU Vet Med Diagnostic Laboratory). Data were analyzed using sampling hour as a fixed effect, and hour LS means were considered different when P ≤ 0.05. There was an effect of hour (P < 0.05) on all blood chemistry measures except anion gap (P = 0.06), phosphorous (P = 0.11), and creatine kinase (P = 0.35). Glucose, total protein, and globulin increased from 0 to 12 h. Creatinine decreased from 0 to 6 h. Albumin decreased from 0 to 24 h. Blood urea nitrogen decreased from 12 to 72 h. Triglycerides increased from 12 to 48 h. Sodium decreased from 0 to 24 h and then from 24 to 48 h. Potassium decreased from 0 to 6 h and increased from 24 to 48 h. Chloride concentrations were greater at 0 and 48 h than 24 h. Bicarbonate was greater at 0 and 72 h than 6, 12, and 24 h. Calcium decreased from 6 to 24 h and increased from 24 to 48 h. Magnesium increased from 0 to 6 h but decreased from 24 to 72 h. Direct bilirubin increased from 0 to 6 h and decreased from 12 to 24 h. Total bilirubin increased from 0 to 6 h and 12 to 24 h and then decreased 24 to 48 h. Aspartate aminotransferase increased from 0 to 72 h, except from 12 to 24 h. Gamma-glutamyltransferase increased 0 to 6 h, decreased 12 to 24 h, and increased from 48 to 72 h. These data demonstrate that blood chemistry changes throughout the first 72 h of life in foals. Sampling time should therefore be taken into consideration when evaluating individual neonates.