Discussion Tyzzer's disease has been reported in a wide variety of animals including mice, rats, gerbils, guinea pigs, hamsters, muskrats, rabbits, raccoons, gray foxes, coyotes, lesser pandas, snow leopards, dogs, cats, horses, cattle, and monkeys. Although there are no reports of Tyzzer's disease in humans, serum antibody titers to the causative organism have been documented. To the authors' knowledge, however, Tyzzer's disease has been reported in birds only once previously. The apparent rare occurrence of Tyzzer's disease in birds is surprising since the organism must be isolated in epithelial cells of chick embryos or in tissue culture because it cannot be propagated on artificial media. The bird of this report was young and had recently been treated for crop stasis, the stress of which could have contributed to the development of clinical disease.
Clinical signs are usually nonspecific and death ensues rapidly.
Multifocal necrosis is randomly distributed and associated with neutrophilic inflammation. Viable hepatocytes bordering the necrotic foci contain numerous bacteria arranged in bundles within their cytoplasm. In cases with myocarditis, bacteria are also present within myocardial cells. However, more recently it has been identified as a C lostridium sp. Since the vegetative phase of the bacterium is labile, survival of the organism outside the host is thought to be in a sporulated form.