Caprine nodular thelitis due to Mycobacterium uberis: A series of 26 cases in 11 dairy goat farms in Western France.

Bovine Nodular Thelitis (BNT) is a granulomatous dermatitis of teat skin associated with acid-fast bacilli. A similar condition has been recorded in a dairy goat flock in France recently. The causative agent was shown to be related to the leprosy-causing bacilli Mycobacterium leprae and M. lepromatosis, then sequenced and named M. uberis. Following the initial report in goats, the aim of this study was to investigate new cases of Caprine Nodular Thelitis (CNT) in the same area to confirm the presence of M. uberis by molecular techniques and to get a better description of the clinical signs and of the affected flocks. Twenty-six animals (25 females and 1 male) from 11 flocks were included in the study. Lesions were located on the udder/teat skin (24/25), on the body skin (6/25) or on the scrotum skin (1/1). Udder skin lesions were circular, nodular and/or ulcerate covered with a crust and associated with supramammary lymph node enlargement. Body skin lesions were located at different parts of the body, showed large necrotizing ulcers with undetermined edges and were associated with regional lymph node enlargement. Histopathological results indicated granulomatous dermatitis and lymphadenitis of varying intensity with no acid-fast bacilli seen after Fite-Faraco staining. M. uberis DNA was amplified from 26 samples out of 47 (udder: 11/22; lymph node: 11/20; body: 4/5). The female goats were mostly older than 4 year of age and originated from breeding units characterized by large flock size and high proportion of goat in continuous lactation.

Tuberculoid nodular thelitis in a dairy goat flock.

An unusual outbreak of teat/udder skin lesions occurred in a dairy goat flock in France. Lesions first appeared as circular, indurated, erythematous areas of skin and progressed to form dark raised haemorrhagic crusts and ulcerative plaques. Histopathological examination revealed marked granulomatous dermatitis with multifocal ulceration. The granulomatous inflammation, with frequent Langhans type multinucleated cells and central caseous necrosis, was indicative of mycobacterial infection. The presence of non-cultivable mycobacteria was confirmed by sequencing PCR products from DNA extracted directly from the lesions and sequences matched a novel mycobacterial pathogen closely related to M. leprae and M. lepromatosis and previously identified in cattle thelitis. The association of nodular gross lesions and tuberculoid granulomas on the teat and lower udder, and the presence of mycobacteria DNA support a diagnosis of tuberculoid nodular thelitis in goats due to mycobacterial infection.