Effects of general anesthesia on plasma colloid oncotic pressure in dogs.

OBJECTIVE

To determine the magnitude of the change in colloid oncotic pressure (COP) associated with general anesthesia in dogs undergoing a variety of elective procedures.

DESIGN

Cohort study.

ANIMALS

50 client-owned dogs.

PROCEDURES

For each dog, preanesthetic and postanesthetic PCV, plasma total solids (TS) concentration, and COP were determined. The procedures requiring anesthesia, volume of crystalloid fluids administered IV, duration of anesthesia, age, weight, and sex were recorded.

RESULTS

Postanesthetic PCV (mean +/- SD, 41.8 +/- 5.4%), TS concentration (6.3 +/- 0.8 g/dL), and COP (19.4 +/- 3.6 mm Hg) were significantly decreased, compared with preanesthetic values (48.8 +/- 5.9%, 7.2 +/- 0.7 g/dL, and 24.4 +/- 4.2 mm Hg, respectively). None of the variables tested could be used to reliably predict changes in COP.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that COP in healthy dogs may decrease by 5 mm Hg on average after general anesthesia and that this decrease may not be reliably predicted by the volume of fluids administered IV during anesthesia or by the concurrent measured decrease in TS concentration.