Abstract
BACKGROUND: Actinobaculum suis is a bacterium known to cause infections of the urogenital tract of sows. Infection can occur through close contact to boars, who frequently carry the pathogen in their preputial diverticulum but do not become clinically diseased themselves. In the current case, Actinobaculum suis was isolated from pyogranuloma of inflamed epididymis in a boar with poor fertility. CASE PRESENTATION: Increased return to oestrus rate, which worsened after the purchase of a new boar, was reported in an organic farm in Switzerland. During herd examination, azoospermia of the boar was diagnosed, and slaughter, followed by examination of its urogenital tract, was carried out. Pathologically, pyogranuloma formation and epididymitis were diagnosed. Bacteriology of the pyogranulomas showed growth of Actinobaculum suis and mixed flora. After the boar was replaced, the return to oestrus rate improved tremendously. CONCLUSION: A close relative of Actinobaculum suis, namely Actinotignum schaalii, has already been associated with epididymitis in humans. Considering the present case and the parallels in human medicine, Actinobaculum suis should be included in the list of differentials of boars with poor fertility.