EFFECTS OF CEPHALOTHIN, CEFAZOLIN, AND CEFMETAZOLE ON THE HEMOSTATIC MECHANISM IN NORMAL DOGS - IMPLICATIONS FOR THE SURGICAL PATIENT

Twenty-six female beagles were used to evaluate the effects of intrave nous and long-term subcutaneous administration of cephalothin, cefazol in, and cefmetazole on platelet function and the coagulation cascade. Platelet aggregation in response to an adenosine diphosphate (ADP) ago nist, bleeding time, platelet count, platelet size, prothrombin time ( PT), and activated partial thromboplastin times (aPTT) were evaluated before and 90 minutes after two intravenous doses (22 mg/kg) of cephal othin, cefazolin, and cefmetazole given at 90-minute intervals. Dogs g iven saline injections were used as controls. Platelet count, platelet size, PT, and aPTT were evaluated after 7 days of subcutaneous admini stration of saline, cefazolin, and cefmetazole (22 mg/kg every 8 hours ). A significant decrease in platelet aggregation in response to ADP w as detected 90 minutes after intravenous administration of cephalothin . Bleeding time was increased significantly 90 minutes after intraveno us administration of cefmetazole. Platelet size was decreased signific antly 24 hours after onset of the study in all animals, including cont rols. No significant changes in platelet count, platelet size, PT, or aPTT were detected after 7 days of subcutaneous administration. Cefazo lin had no adverse effects on platelet aggregation in response to ADP, bleeding time, platelet count, platelet size, PT, or aPTT. Therefore, cefazolin should be considered as a perioperative antibiotic in dogs with conditions predisposing to hemostatic complications. (C) Copyrigh t 1995 by The American College of Veterinary Surgeons