Unusual Epidemic of Tyzzer’s Disease in Commercial Rabbit Breeders: Clinical, Pathological, and Therapeutic Observations

<i>Clostridium piliforme</i> (Cp) is a pleomorphic spore-forming obligate intracellular bacterium and the causative agent of Tyzzer's disease. The condition affects multiple species, including rabbits, in which the disease is sporadic in recently weaned animals. This report details a case of disease caused by Cp observed exclusively in breeding rabbits of a commercial farm. The clinical manifestations were a higher mortality rate in does and late-gestation abortions. We performed necropsy and further microbiological, parasitological and histopathological analyses. Anatomopathological lesions were suggestive of Tyzzer's disease and the presence of Cp was confirmed by PCR. Parasitological analysis tested negative and standard bacteriological examination of intestines revealed a high load of <i>Escherichia coli</i> and <i>Clostridium perfringens</i>, which were considered secondary pathogens. <i>Chlamydophila</i> sp. and <i>Toxoplasma gondii</i> infections were excluded by PCR as causative agents of abortions. Moreover, in the months following the diagnosed outbreak, episodes of subcutaneous edema occurred in multiple does and young breeders born after the resolution of the epidemic. The constant reduction in the use of antimicrobials in recent years could make some neglected diseases emerge again. Therefore, it is crucial to suspect such uncommon pathologies in commercial rabbitries to properly manage them on farms.