Occurrence of purulent mandibular and maxillary osteomyelitis associated with Pseudomonas aeruginosa in a sheep flock in south-west of Iran

This report describes an outbreak of purulent mandibular and/or maxillary osteomyelitis caused by Pseudomonas aeruginosa in a sheep flock located in the Khuzestan province, Iran. Jaw bones of almost 100 out of 500 mature sheep in a flock became severely deformed with a variably sized firm swelling, without any signs of inflammation in the surrounding soft tissues. The affected animals showed anorexia, depression, swelling of the mandibular and/or maxillary area, loss of cheek teeth and poor body condition. ‏These animals were gradually culled in a period of 3 months. Postmortem examination showed a hard swelling of jaw bones with dirty greenish pus that filled alveolar molar teeth cavities. Histopathologic findings revealed necrotic areas surrounded by mixed population of inflammatory cells with exuberant fibrosis around some area of the lesions and irregular trabeculae of woven bone. In bacteriology, pure culture of P. aeruginosa was isolated from all of 7 sampled sheep. Based on clinical examination, radiography, histopathological features and bacteriology, the lesions were diagnosed as chronic suppurative osteomyelitis caused by P. aeruginosa. According to bacteriological results, the likely source of bacterial infection in this study was drinking water.