Clinical biochemistry of pregnant and nursing mares.

The study investigates physiological changes in blood substances of pregnant and nursing mares and determines whether these changes are significant enough to necessitate separate reference points for these special conditions. The researchers found that while most biochemical values remained stable, significant variations were observed in elements like triglycerides, potassium, bilirubin, total CO2, and the anion gap during lactation, therefore proposing separate reference intervals for lactating horses.

Study Purpose and Design

• The study aimed to understand the physiological changes in serum clinical biochemistry analytes in pregnant and nursing mares. It also aimed to determine whether these changes were significant enough to warrant separate reference intervals for pregnant or lactating horses.
• This research was conducted on 42 horses of various breeds who were pregnant at the time of entry into the study. Their blood was tested monthly until birth, and for 20 of the horses, testing continued until the foaling period was complete.
• The researchers employed standard methods using automated analyzers to recognize serum biochemistry values. Kruskal-Wallis 1-way ANOVA method was used for data analysis. If any significant differences were found, Dunn’s multiple comparisons were utilized.

Study Findings

• Results showed that the concentrations of serum triglyceride, potassium, creatinine, and total bilirubin were lower during lactation than throughout pregnancy. Minimal decrease was also spotted at 2 time points during lactation for serum calcium concentration.
• On the contrary, during pregnancy, triglyceride concentration was recorded highest during mid-gestation, bilirubin and creatinine values rose, while potassium and calcium remained consistent.
• Serum phosphate concentration dropped during mid-gestation and was highest during lactation. The amount of total CO2 was maximal, and anion gaps were minimal during mid-gestation.
• No significant variations were detected in serum albumin, globulin, albumin:globulin ratio, total protein, or glucose values.
• Compared with a reference group of open, non-lactating mares, serum triglyceride, potassium, bilirubin, and total CO2 concentrations were lower, and anion gap was higher in mares who were nursing or lactating.

Study Conclusion

• Though majority of biochemical values maintained relative stability, pregnant and lactating phases exhibited significant differences.
• The observed changes in the concentrations of triglycerides, potassium, bilirubin, total CO2, and anion gap during lactation were substantial enough to necessitate separate reference intervals for lactating horses according to the findings of this study.