Abstract
Abscess disease (caseous lymphadenitis and Morel disease) is a worldwide contagious bacterial disease of sheep and goats and is adversely affecting the development of the sheep industry in Saudi Arabia. Fifteen sheep and 12 goat farms at Qassim region, central Saudi Arabia, were surveyed during September and October 2008 for the determination of the prevalence and the etiology of abscess disease. One hundred and twenty pus samples were collected from affected external lymph nodes of clinically-ill sheep and goats and from infected internal lymph nodes and organs condemned during meat inspection in the slaughterhouses, for the isolation and identification of pathogenic bacteria causing sheep abscess disease. The prevalence of abscess disease varied between 5%-44.1% in sheep farms, being highest in the Najdi breed, and between 2.2%-6.5% in goat farms. Males of both sheep and goats had the highest rate of infection compared to females (p <0.01). Bacterial isolates were obtained from 97 out of the 120 collected pus samples (80.83%). The remaining 23 samples were sterile. Corynebacterium pseudotuberculosis and Staphylococcus aureus subsp. anaerobius accounted for about 54% of isolates, with almost equal frequencies (p=0.5). Other pyogenic bacteria such as S. aureus, Streptococci, Pseudomonas aeruginosa, Actinomyces pyogenes were also isolated from infected abscesses. They represented about 46% of the isolated etiological agents of sheep abscesses. This explains why available vaccines (bactrins) against caseous lymphadenitis (CLA) are poorly protective against abscess disease in Saudi Arabia.