Clostridial muscle infections following intramuscular injections in the horse

Abstract

A variety of diseases have been associated with Clostridium species in the horse, including tetanus, botulism, enteritis, enterotoxemia, hepatic abscesses, hepatic necrosis, and myonecrosis, with and without cellulitis.~ 15 In humans, clostridial diseases are generally classified by disease syndrome rather than by causative organism (e.g. gas gangrene, septicemia, gastroenteritis or food poisoning, uterine infections, tetanus, etc.). ~6 Tetanus is caused exclusively by CI. tetani, but the other syndromes can be caused by one or more species, and one species may be capable of causing more than one syndrome. ~6 It is, therefore, accepted in human medicine that the diseases caused by a specific Clostridium may vary depending on local tissue factors, virulence, toxin-producing capability, and potency of toxins produced. Case reports of clostridial muscle infections in the horse describe several different syndromes produced by a variety of clostridial species? 7'8 l~ ~31415 Some of these syndromes have been called malignant edema, others myositis, and one was a focal abscess. In common with other mammalian species? it appears that clostridial infections of equine muscle can produce a variety of clinical syndromes. It is, therefore, p robab ly unwise to a t t em p t a detailed classification based either on the clinical and pathological findings or one based on the causative organisms. In this paper describing 5 horses with clostridial infections of muscles, no attempt to distinguish specific disease entities will be made. It is the authors' opinion that they represent different degrees of the same problem, and reflect the specific local tissue conditions of each infection and the types of toxins produced. Clostridia are large anaerobic Gram-positive sporeforming rods, but can withstand short periods of low oxygen tension. They are commonly found in the soil and in the intestinal tracts of domestic animals. 3 They may also be normal flora of skin and mucous membranes. ~6 Under certain circumstances, infections can develop in muscle. Two modes of infection are believed to exist. 3 The first, typically described as the mechanism of blackleg infection in cattle, suggests that clostridial spores are absorbed from