Hemostatic function in swine as influenced by warfarin and an oral antibacterial combination

Pertinent literature on naturally occurring hemorrhagic diseases in poultry and livestock were reviewed and compared with reports on recent outbreaks of a hemorrhagic syndrome in swine. Epizootiologic, clinical, and hematologic data from porcine hemorrhagic disease suggest vitamin K-responsive hypoprothrombinemia. In weanling pigs, the toxicity of warfarin was compared with that in swine given tylosin and sulfamethazine antibacterial combination versus those given warfarin only. Toxicosis was induced in weanling swine fed warfarin daily at dose level of 0.055 mg/kg of body weight. Approximately 5 days after feeding was started, signs of poisoning appeared: lameness, anorexia, subcutaneous hematomata, melena, and periarticular enlargement. Administration of warfarin at dose level of 0.017 mg/kg did not cause clinical toxicosis, and 0.028 mg/kg produced significant increases in one-stage prothrombin time (OSPT) and activated partial thromboplastin time (APTT), but no evidence of clinical bleeding. When tylosin-sulfamethazine antibacterial combination was fed at normal and high dose levels concurrently with warfarin at dose level of 0.017 mg/kg of body weight, increase of clotting time, OPST, or APTT did not occur due to antibacterial influence. The antibacterial combination fed alone did not produce changes in clotting time, OSPT, APTT, fibrinogen, total protein, differential leukocyte count, or packed cell volume.