Rabbit Enteropathies on Commercial Farms in the Iberian Peninsula: Etiological Agents Identified in 2018–2019

SIMPLE SUMMARY: Digestive disorders are the main cause of economic damage in rabbit farms and, usually, antibiotic treatment is the first choice to control them. Nevertheless, a broad range of infectious agents can be involved in such disorders, as we have observed in our diagnosis work as a veterinary diagnostic laboratory. In this study, a global and updated overview of the frequency of detection of those etiological agents is provided. We have seen differences depending on the age of the affected rabbits, with young rabbits (<15 days old) being the most affected by enteropathogenic Escherichia coli strains, while in preweaning and growing rabbits, a coinfection of two or three pathogens is the most prevalent situation. Clostridium spiroforme and E. coli are the main bacterial agents detected in preweaning rabbits, but enterotoxigenic Bacteroides fragilis has just appeared as a new possible emergent pathogen. Coinfections between bacteria (C. spiroforme and E. coli), parasites (Eimeria spp.), and viruses (rotavirus) are much more frequent than simple infections in growing rabbits; for this reason, complete laboratory studies are required to establish on-farm disease control measures. ABSTRACT: Digestive disorders are the main cause of economic damage to rabbit farms. This article provides a global and updated overview of the diverse etiological agents causing them, since 757 clinical cases were analyzed during 2018 and 2019—Ninety-five from young rabbits (<15 days old), 117 from preweaning rabbits (15–35 days old), and 545 from growing rabbits. Etiological diagnosis was carried out by bacteriological culture and a set of real time polymerase chain reaction (qPCR) tests for the detection of enteropathogenic Escherichia coli (EPEC), Clostridium spiroforme, C. perfringens, rotavirus A, Bacteroides fragilis, and Eimeria spp. Also, 40 EPEC and 38 non EPEC isolates were investigated for the presence of other colonization factors (afr2, ral, liftA, and paa) by qPCR. EPEC is the most prevalent agent in young rabbits, and although different virulence profiles have been found among EPEC isolates, the liftA+, ral+, and paa+ profile is the most prevalent. C. spiroforme and EPEC are the more frequently detected pathogens in preweaning rabbits, but B. fragilis appears to be a new possible emergent pathogen. In growing rabbits, diverse co-infections between C. spiroforme, Eimeria spp., EPEC, and rotavirus are much more frequent than infections due to only one of them. Other pathogens detected in very few cases are Salmonella spp. and Enterococcus hirae.