An outbreak of abscess disease in sheep flocks associated to Arcanobacterium pyogenes in Esfarayen, Northeastern of Iran Aslani MR1, Rad M2, Binas N3, Afshari A3 1Professor of School of Veterinary Medicine Ferdowsi University Of Mashhad 2Associate Professor of School of Veterinary Medicine Ferdowsi University Of Mashhad 3Student of School of Veterinary Medicine Ferdowsi University Of Mashhad Introduction: Although abscesses are relatively common in most animal species, they usually occur sporadically and often occur following a puncture wound or injury, and they can be caused by a variety of bacteria common in all environments such as streptococci and staphylococci. However, classic abscess disease of sheep and goats caused by Corynobacterium pseudotuberculosis characterized with lymph node suppuration. Arcanobacterium pyogenes infection is common in different animal species but caused sporadic diseases such as mastitis, arthritis, abortion, liver abscess and bone infection. Objectives: To describe an outbreak of abscess disease associated with Arcanobacterium pyogenes. Materials and Methods: This report describes an outbreak of abscess disease in sheep flocks located in Esfarayen, Northeastern of Iran. The flocks consisted of 20 – 80 animals of different age ranging from 6-12 months of Kordi bred. The sheep were kept indoor for fattening where they received a mixture of alfalfa hay and barley. Twenty to 30% of animals in different flocks were showing one or several abscess of superficial lymph nodes which were more frequent in pharyngeal area. Abscesses were round with diameter of 3-15cm, soft and fluctuating in consistency when palpated. Clinical cases were first observed 4 weeks after introducing of metal feed troughs with rough and sharp edges which eroding pharyngeal skin area. A number of abscesses were aseptically aspirated and samples were taken in sterile condition. The contents of abscesses were odourless, viscid and white green in clour. Results: Gram stained smears of aspirates from abscesses revealed a numbers of small Gram-positive rods. The samples were cultured in aerobic and anaerobic condition. After 48 hours incubation a pure culture of small colonies were visible surrounded by a narrow zone of complete hemolysis. Gram-stained smear from colonies revealed the typical pleomorphic, Gram-positive rods. The morphologic and biochemical features of the organisms were directed to identification of Arcanobacterium pyogenes. Conclusion: Outbreak of abscess disease due to Arcanobacterium pyogenes is uncommon in animals and this report showed that the organism can infect a number of sheep through skin abrasions leading to abscess development. A combination of treatment, culling and management of the environment can reduce the risk of infection or eliminate the disease over time.

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