Effects of preoperative administration of hypertonic saline or pentastarch solution on hematologic variables and long-term survival of surgically managed horses with colic.

Objective: To compare the effects of preoperatively administered pentastarch (10% concentration in isotonic saline [0.9% NaCl] solution) and hypertonic saline (7.2% NaCl) solutions on PCV and circulating total protein (TP) concentration in horses with colic undergoing emergency exploratory laparotomy and to assess survival rates of horses that received each treatment.

Design: Prospective, randomized study.

Animals: 100 horses with signs of abdominal pain and PCV ≥ 0.46 L/L. Procedures-Horses received a 4 mL/kg (1.8 mL/lb) dose of pentastarch solution (n = 50) or hypertonic saline solution (50) over a 10- to 20-minute period before anesthetic induction. Blood samples were collected at the time of evaluation and ≤ 5 minutes after fluid resuscitation; changes in PCV and TP concentration were compared. Survival was evaluated by Kaplan-Meier and Cox proportional hazards analyses.

Results: Age, weight, sex, PCV, and heart rate on initial examination were similar between treatment groups. Hypertonic saline solution treatment resulted in a significantly greater reduction in PCV (median change, -0.14 L/L) than did pentastarch treatment (median change, -0.07 L/L). Reduction in TP concentration was also significantly greater after hypertonic saline solution treatment (median change, -16 g/L) than after pentastarch treatment (median change, -2 g/L). Long-term survival was not significantly different between groups.

Conclusions And Clinical Relevance: Despite a greater reduction in preanesthetic hemoconcentration following administration of hypertonic saline solution (4 mL/kg infusion, once), no difference in overall long-term survival was found between horses that received this treatment and those that received an equal volume of pentastarch solution. Findings suggested that, in a clinical setting, either of these fluids would be appropriate for preoperative fluid resuscitation in horses with colic.