Avian Mycobacteriosis and Molecular Identification of Mycobacterium avium Subsp. avium in Racing Pigeons (Columba livia domestica) in Greece

Abstract

In this report, cases of avian mycobacteriosis in two lofts of racing pigeons are described. Three racing pigeons of 2-year old from the first loft (A) and four racing pigeons of 4–5 years old from the second loft (B) were submitted to the Unit of Avian Medicine for clinical examination and necropsy. In the case history chronic and debilitating disease was reported. The clinical signs included emaciation, depression, lameness, periorbital swelling and diarrhea, although the appetite was normal. Post mortem lesions involved an enlarged spleen with multiple different sized yellow nodules. Similar lesions were also observed in the liver, conjunctiva of the inferior eyelids and in the femoral bone marrow. The suspicion of avian mycobacteriosis was based on history, clinical signs and typical lesions. In order to confirm the diagnosis, histopathology was performed on tissue sections and revealed the presence of multiple granulomas with central necrosis. In addition, Ziehl-Neelsen positive bacilli were observed in histological sections and smears from the granulomas of the affected tissues. Molecular analysis identified the causative agent as Mycobacterium avium subsp. avium. This is the first case report of avian mycobacteriosis in Greece, which describes the presence of granulomatous conjunctivitis and the molecular identification of M. avium subsp. avium as the causative agent in racing pigeons.