Determination of reference intervals for umbilical cord arterial and venous blood gas analysis of healthy Thoroughbred foals.

This research paper examines the use of umbilical cord blood gas analysis in determining oxygen levels in newly-born horse foals still in the womb. The study discovered both the straightforward nature of obtaining umbilical cord samples and identified reference intervals for the healthy levels of various gas levels in the blood.

Objective and Methodology

• The research aims to verify the effectiveness of using umbilical cord blood gas analysis to evaluate prenatal oxygenation in horse neonates. While this method is widely used in the assessment of human neonates, its utility in equine neonatology hasn’t been comprehensively examined before.
• Healthy Thoroughbred foals, born after a gestation period of over 320 days from healthy mares having uncomplicated pregnancies, were analyzed in the study. The assessment was conducted at a single stud farm, and the selection aimed at ensuring a uniform baseline for the study.
• Post-birth, paired arterial and venous blood samples from the umbilical cord were collected and analyzed for lactate and blood gas concentration. Appropriate Apgar scores, used to assess the physical condition of a newborn, were assigned immediately and 10 minutes after birth.
• Each foal was monitored for the first 28 days of their life for signs of perinatal asphyxia syndrome, a condition that typically arises due to lack of oxygen.
• The study excluded foals based on abnormalities in the second stage of labor, abnormal Apgar scores, and gross and histological placental assessment.
• The methods for analysis included a Student’s t-test, Pearson’s correlation, and the robust method. A P value of equal or less than 0.05 was considered significant.

Results and Findings

• The procedure of obtaining umbilical cord samples was found to be straightforward with minimal disturbance to the natural foaling environment.
• Out of 34 foals studied, 7 were removed from the analysis because of premature placental separation deliveries.
• Average time for the second stage of labor and blood gas analysis was found to be around 17.3 minutes and 5.0 minutes, respectively.
• Reference Intervals (RI) were identified for arterial and venous pH, PO (oxygen partial pressure), PCO (carbon dioxide partial pressure), SO (oxygen saturation), bicarbonate, base excess, TCO (total carbon dioxide) and lactate.
• Arterial samples were found to have lower pH, PO, and SO and higher PCO and lactate than venous samples.
• A positive correlation was found between initial Apgar score and umbilical arterial SO, and a negative correlation with umbilical arterial TCO.

Conclusion

• Umbilical cord sampling was found to be simple and minimally disruptive with easily identifiable reference intervals for blood gas measurements.
• However, findings call for additional data from a larger population of healthy and unhealthy foals to ensure accurate validation of this method for assessing prenatal oxygenation in horse neonates.