Abstract
Abscess diseases of sheep (caseous lymphadenitis, CLA, caused by Corynebacterium pseudotuberculosis, and Morel disease, caused by Staphylococcus aureus) are endemic in Saudi Arabian sheep farms. The etiology and pathology of visceral abscess disease is poorly documented for Saudi Arabian sheep. This study was carried out to investigate the etiology and pathology of internal (visceral) abscesses of sheep at Qassim region, central Saudi Arabia. One hundred and twenty abscessed internal lymph nodes were collected from sheep with single organ-lymph node abscesses, and slaughtered in Qassim abattoirs. All the surveyed sheep had clinical external abscess disease. Animals with multiple internal abscesses were discarded from survey. Pus samples obtained from the lymph nodes were cultured aerobically and anaerobically. Isolates were obtained from 99 infected lymph nodes (82.5%). The numbers of recovered bacterial isolates were as follows: Staphylococcus aureus (39), Corynebacterium pseudotuberculosis (27), Staphylococcus aureus subsp. anaerobicus (25), Streptococcus spp. (6) and Pseudomonas aerugenosa (2). These organisms were isolated from the following lymph nodes: hepatic (51), mediastinal (42) and renal (6). Identification of C. pseudotuberculosis was confirmed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) targeting the phospholipase D (PLD) gene.