Effects of aerobic and anaerobic fluid collection on biochemical analysis of peritoneal fluid in healthy horses and horses with colic.

OBJECTIVE

To determine whether in healthy horses and those with colic, exposure of peritoneal fluid to room air affects values obtained on biochemical analysis.

STUDY DESIGN

Prospective study.

ANIMALS

Adult horses with a primary complaint of acute abdominal pain (n=29) and 12 healthy horses.

METHODS

Peritoneal fluid was aseptically collected under aerobic and anaerobic conditions. After collection, pH, PCO(2) , PO(2) , HCO(3) (-) , Na(+) , ionized Ca(2+) , K(+) , lactate, and glucose were immediately measured using a commercial blood gas analyzer. Biochemical variables were compared between aerobically and anaerobically obtained samples using a paired t-test.

RESULTS

In healthy horses, peritoneal fluid samples collected under anaerobic conditions had higher PCO(2) and ionized Ca(2+) and lower PO(2) , HCO(3) (-) , and pH compared with samples exposed to air. No differences were observed for K(+) , Na(+) , glucose, and lactate. In horses with colic, samples collected anaerobically had higher PCO(2) , ionized Ca(2+) , Na(+) , and glucose and lower PO(2) , HCO(3) (-) , and pH value compared with samples exposed to air. No differences were observed for K(+) and lactate.

CONCLUSION

Exposure of peritoneal fluid to room air had a significant effect on pH, PCO(2) , PO(2) , and variables associated or dependent on changes in pH such as HCO(3) (-) and ionized Ca(2+) . Interpretation of biochemical analysis of peritoneal fluid may be influenced by sample collection method.