The resultant toxemia produces shock, circulatory collapse and frequently death. Clinically, the owner discovers a horse in severe distress one to three hours after feeding. Profuse sweating, a rapid, thready pulse, injected mucous membrane, and a distended abdomen or bloated appearance are usually noted. Most of these horses fail to respond to any significant degree to routine colic therapy. Practitioners have reported response in some cases to intravenous infusion of 100250 cc of Colostridium BCD antitoxin of equine origin.
Postmortem lesions indicate congestion of the lungs, myocardilum, adrenals, and liver.
The intestines are distended with gas but may appear blanched rather than congested or inflamed. A more advanced state of autolysis than is usual for the length of time following death is present. Pathologists usually question the difference between actual and expected tissue changes. Frequently, excessively large numbers of Clostridium perfringens can be cultured. These findings help explain the clinical appearance of the horse.