Effects of tromethamine buffer on coagulation variables and ionized calcium concentration in dogs.

OBJECTIVE: To evaluate coagulation variables in 2 groups of dogs after tromethamine administration. ANIMALS: 13 Beagles. PROCEDURES: Both groups of dogs received a 30-minute IV infusion of 10 ml of 0.3M tromethamine/kg of body weight. In unsedated dogs (group 1, n = 8), prothrombin time, activated partial thromboplastin time, normalized ionized calcium concentration, platelet numbers, and platelet function were measured prior to treatment, at the end of the infusion, and 1 hour after the infusion. In xylazine-sedated dogs (group 2, n = 5), buccal mucosal bleeding time and plasma percentage of von Willebrand factor antigen were measured before and 1 hour after infusion, and fibrin degradation products concentration was measured 1 hour after infusion. Platelet function was assessed by determining platelet aggregation and by measuring ATP release from the aggregating platelets over 6 minutes, using a whole blood aggregometer, with 20, 10, and 5 microM ADP and 5 and 10 micrograms of collagen/ml as platelet activation agonists. RESULTS: There was no significant change in any of the variables measured in either group of dogs, compared with baseline values. CONCLUSIONS AND CLINICAL RELEVANCE: When administered to healthy dogs, tromethamine does not change the coagulation indices measured.