Circulating endotoxin-like substance(s) and altered hemostasis in horses with gastrointestinal disorders: an interim report.

Twenty-three horses with clinical signs of gastrointestinal disease were evaluated once or serially during the course of the disease for the presence or absence of circulating endotoxin-like substances (ET+ or ET-) and whether the horses were negative, positive, or very positive for serum fibrin/fibrinogen degradation products (FDP-, FDP+, or FDP++). In addition, platelet count, activated partial thromboplastin time (APTT), and 1-stage prothrombin time (OSPT) were measured. When examined initially, 5 horses were ET-/FDP-, 8 were ET-/FDP+, 7 were ET+/FDP-, 3 were ET+/FDP+, and none was ET+/FDP++. Eight horses were evaluated serially and the following changes were noted: 1 ET-/FDP- horse became ET+/FDP++; 1 ET-/FDP- horse became ET-/FDP+; 1 ET-/FDP- horse became ET+/FDP-; 2 ET-/FDP+ horses became ET+/FDP++; 1 ET+/FDP- horse became ET+/FDP+ (++); and 2 ET+/FDP- horses became ET-/FDP-. At the last examination, 4 horses were ET-/FDP- and all survived; 7 were ET-/FDP+ and only 1 was euthanatized; 5 were ET+/FDP- and only 2 were euthanatized; and 7 were ET+/FDP+ or ++, and 5 horses died or were euthanatized. The relationship between ET and FDP is discussed and a working model of endotoxemia and gastrointestinal disease in the horse is presented.