Effects of 6% hetastarch (600/0.75) or lactated Ringer's solution on hemostatic variables and clinical bleeding in healthy dogs anesthetized for orthopedic surgery

Objective To evaluate and compare hemostatic variables and clinical bleeding following the administration of 6% hetastarch (600/0.75) or lactated Ringer's solution (LRS) to dogs anesthetized for orthopedic surgery. Study design Randomized blinded prospective study. Animals Fourteen, healthy adult mixed-breed hound dogs of either sex, aged 11-13months, and weighing 20.8±1.2kg. Methods The dogs were randomly assigned to receive a 10mLkg^-1 intravenous (IV) bolus of either 6% hetastarch (600/0.75) or LRS over 20minutes followed by a maintenance infusion of LRS (10 mLkg^-1hour^-1) during anesthesia. Before (Baseline) and at 1 and 24hours after bolus administration, packed cell volume (PCV), total protein concentration (TP), prothrombin time (PT), activated partial thromboplastin time (APTT), von Willebrand's factor antigen concentration (vWF:Ag), factor VIII coagulant activity (F VIII:C), platelet count, platelet aggregation, colloid osmotic pressure (COP) and buccal mucosal bleeding time (BMBT) were measured. In addition a surgeon who was blinded to the treatments assessed bleeding from the incision site during the procedure and at 1 and 24hours after the bolus administration. Results Following hetastarch or LRS administration, the PCV and TP decreased significantly 1-hour post-infusion. APTT did not change significantly compared to baseline in either treatment group, but the PT was significantly longer at 1-hour post-infusion than at 24hours in both groups. No significant change was detected for vWF:Ag, FVIII:C, platelet aggregation or clinical bleeding in either group. The BMBT increased while platelet count decreased significantly at 1-hour post-infusion in both groups. The COP decreased significantly in both treatment groups 1-hour post-infusion but was significantly higher 1-hour post-infusion in the hetastarch group compared to the LRS group. Conclusions and clinical relevance At the doses administered, both hetastarch and LRS can alter hemostatic variables in healthy dogs. However, in these dogs undergoing orthopedic surgery, neither fluid was associated with increased clinical bleeding.