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

## TL;DR

This paper reports a rare outbreak of Tyzzer’s disease in adult female rabbits on a commercial farm, highlighting its clinical signs, diagnosis, and management.

## Contribution

This is one of the first detailed reports of Tyzzer’s disease in adult female rabbit breeders, including clinical, pathological, and therapeutic observations.

## Key findings

- Tyzzer’s disease was confirmed in breeding rabbits via PCR and histopathology.
- Secondary infections like Escherichia coli and Clostridium perfringens were identified in affected rabbits.
- Subcutaneous edema occurred in rabbits after the outbreak, possibly linked to reduced antimicrobial use.

## Abstract

Tyzzer’s disease is a bacterial infection caused by Clostridium piliforme. While described in various animal species, it remains an uncommon disease in commercial rabbitries today, particularly in breeders. The clinical presentation and gross pathology may be variable and mislead the diagnosis towards other more common bacterial infections. This case report aims to provide a comprehensive overview of a Tyzzer’s disease case affecting only does in a commercial rabbitry. To the authors’ knowledge, this is one of the first reports to cover the clinical presentation, gross pathology, laboratory diagnosis, histopathology, and treatment of the disease affecting only adult female breeders.

Clostridium piliforme (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 Escherichia coli and Clostridium perfringens, which were considered secondary pathogens. Chlamydophila sp. and Toxoplasma gondii 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.