Septicaemic pasteurellosis in free-range pigs associated with an unusual biovar 13 of Pasteurella multocida

Biochemical profiles, PFGE typing and MLST analysis were used to investigate an outbreak of septicaemic pasteurellosis in a free-range pig farm in Spain. Signs of coughing, dyspnoea and a visible inflammation of the ventral area of the neck (jowl), which acquired a cyanotic and necrotic appearance, were the characteristic findings in affected animals, associated with a high morbidity (70%) and case mortality (95%). Diffuse, haemorrhagic and fibrinous pleuroneumonia and acute, focally extensive and haemorrhagic myositis and panniculitis were observed in the histopathological analysis from three analyzed animals. Pasteurella multocida subsp. multocida, capsular type B, biovar 13 was isolated in pure culture from lung, submandibular tissue (jowl), liver, spleen and kidney tissue from diseased pigs. After PFGE typing, all P. multocida isolates displayed undistinguishable macrorestriction patterns with Bsp120I restriction enzyme demonstrating that the infection was caused by a single strain. With the multihost P. multocida MLST database, all P. multocida isolates were assigned to the new sequence type ST47 which was highly related with other bovine isolates of P. multocida type B associated with haemorrhagic septicaemia. This is the first description of an outbreak of septicaemic pasteurellosis in free-range pigs associated with P. multocida type B of the unusual biovar 13. The communication and complete diagnosis of cases of swine septicaemia and the possible role of pigs as reservoirs of this new pathogen must be evaluated to determine the importance of this disease for pigs.