Antithrombin III (ATIII) Activity in Plasmas from Normal and Diseased Horses, and in Normal Canine, Bovine and Human Plasmas

Antithrombin-III activity in plasma of healthy and sick cattle

Antithrombin-III (AT-III) activity was determined in the plasma of 32 healthy cows. The range of activities was between 105 and 160 per cent of a human reference plasma; the median activity was 132.5 per cent, and the 5 per cent and the 95 per cent quartiles were 111.1 per cent and 153.9 per cent of the standard. The activity of AT-III was also determined in 82 cows with a variety of internal diseases. In cows with hepatopathy, acute enteritis, generalised peritonitis, blood loss, idiopathic cardiomyopathy, glomerulonephritis and disseminated coagulopathy, the activity of AT-III was lower than in healthy animals. The lower values were due to decreased synthesis, increased consumption, or the loss of AT-III. An acquired deficiency of AT-III appears to favour the development of thrombophlebitis.

Heparin: a review of its pharmacology and therapeutic use in horses

Heparin is used clinically in horses to treat hemostatic abnormalities associated with severe gastrointestinal disease, septicemia, and endotoxemia. The primary anticoagulant effect of heparin is through the suppression of thrombin-dependent amplification of the coagulation cascade, and inhibition of thrombin-mediated conversion of fibrinogen to fibrin. Heparin may be of benefit in preventing the complications associated with hypercoagulable states such as jugular vein thrombosis, laminitis, and organ failure. Heparin may also be beneficial in the prevention of intraabdominal adhesions after gastrointestinal surgery, and in amelioration of hemodynamic abnormalities associated with endotoxic shock. Because a sequential rise in serum heparin concentration occurs during a uniform dosage regimen, a decreasing dosage regimen is recommended. The initial dose recommended is 150 U heparin/kg body weight subcutaneously, followed by 125 U heparin/kg body weight subcutaneously, every 12 hours for six doses. The dose should be decreased to 100 U heparin/kg body weight subcutaneously, every 12 hours, after the seventh dose. Anemia, hemorrhage, thrombocytopenia, and painful swelling at injection sites are complications of heparin administration in horses.

Antithrombin III activity in horses with colic: an analysis of 46 cases

Antithrombin-III (AT-III) activity was measured at the time of admission in 46 horses referred with colic. Differences in AT-III activities between animals treated medically or surgically and survivors or non-survivors were compared. The mean AT-III values for the horses treated medically (76.2 per cent), surgical survivors (69.5 per cent) and surgical non-survivors (55.9 per cent) were significantly different from the reference value for healthy adults (92 to 108 per cent). The mean AT-III activity of the survivors was significantly (P less than 0.01) greater than that of the nonsurvivors. The majority of the survivors (11 to 13 horses) had AT-III activities exceeding 60 per cent of normal, whereas that of 10 of the 14 non-survivors was less than 60 per cent of normal. There was an apparent distinction between the survivors and non-survivors at approximately 60 per cent of normal AT-III activity.

Plasma plasminogen concentrations in clinically normal horses: the effect of age, sex and pregnancy

Plasma concentrations of plasminogen were determined in 28 clinically normal horses, including 13 adult geldings, five non-pregnant mares, five pregnant mares and five yearlings (two fillies, three geldings). Plasminogen was quantitated by a chromogenic assay based on activation of plasmin by excess urokinase. The overall mean plasma plasminogen for these horses was 2.94 +/- 0.54 CTA units (casein units, as defined by the Committee on Thrombolytic Agents) per ml. There were no significant differences in mean plasma plasminogen values among adult geldings, non-pregnant mares, pregnant mares or yearling horses (P greater than 0.05).

Recognition and management of disseminated intravascular coagulation in horses

This article reviews normal hemostasis in order to provide the reader with the basis for understanding the pathogenesis and manifestations (both clinical and laboratory) of disseminated intravascular coagulation (DIC) in horses. DIC is subsequently discussed. The diagnosis and treatment of DIC in horses are also described.