Heparin anticoagulant therapy in equine colic.

In horses with large bowel disease, those with circulating endotoxins but no evidence of altered hemostasis had a good prognosis for survival. Those with circulating endotoxins and evidence of altered hemostasis (fibrin degradation products) had a poor prognosis. Portal vein infusion of endotoxins over 24 hours caused hoof discomfort, evidenced by shifting of weight and standing with all 4 feet together, and a decreased hoof temperature. Clinical signs appeared within 30 minutes of initiation of infusion and subsided within 4 hours despite continued infusion. Long-term heparin therapy results in rapid depletion of RBC but no detectable bleeding. Heparin therapy should be initiated before colic surgery is begun. Coagulation is monitored with the activated partial thromboplastin time. Heparin should initially be given IV, followed by SC or intrafat injections, and should never be given IM. The anticoagulative effects of heparin can be reversed with protamine sulfate.