Escherichia coli in the rabbit: Commensal or pathogenic

Colibacillosis is one of the most significant enteric diseases in rabbits, particularly in intensive production, and responsible for significant economic losses due to growing performance loss, mortality, poor growth performances, treatment, and veterinary costs. This book chapter provides an overview of the epidemiology, pathogenesis, and clinical signs of colibacillosis in rabbits. The disease primarily affects young rabbits, with two clinical courses observed depending on their age. The main risk factors associated with the disease are poor environmental control, hygiene (biosecurity), crowding and stress, poor nutrition (including inadequate or imbalanced diets), genetics, other concomitant diseases (e.g. intestinal or respiratory), and environmental factors, among others. The most significant serotypes in rabbits include O103, O15:H, O109:H2, O103:H2, O128, and O132. The main macroscopic lesions observed at necropsy consist of two main presentations: congested epithelium and oedema with fluid content. The attaching and effacing lesions on the small intestine are considered the hallmark of infection, which may be found with histopathological analysis. Clinical diagnosis can be achieved through information collection with the anamnesis, observation of clinical signs, and laboratorial analysis. This book chapter will serve as a useful resource for veterinarians and rabbit farmers in understanding the epidemiology, pathogenesis, and clinical signs of colibacillosis in rabbits.