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.