Effect of equine ehrlichial colitis on the hemostatic system in ponies.

Hemostatic function was determined in 10 ponies at various times after inoculation with Ehrlichia risticii to determine whether equine ehrlichial colitis (EEC) caused changes in the hemostatic system and to determine the prognostic value of hemostatic function tests during EEC. Mean platelet count; plasma fibrinogen, fibronectin, factor VIII: coagulant, alpha 2-antiplasmin, and plasminogen values; and serum concentrations of fibrin/fibrinogen degradation products changed significantly (P less than 0.05) from base line (day 0, before inoculation) during 18 days after inoculation with E risticii. Four ponies that died or were euthanatized because of severe clinical signs of EEC had significantly (P less than 0.05) greater mean plasma fibrinogen concentrations plasma factor VIII:coagulant values, and activated partial thromboplastin times immediately before death than did the 6 surviving ponies. Factor V concentrations were significantly (P less than 0.05) lower on postinoculation days 10 and 20 in nonsurvivors. Seemingly, changes in hemostasis took place during EEC. Ponies that did not survive EEC had greater laboratory evidence of coagulopathy.