Introduction and objective:
One of the main health threats to the endangered European bison (Bison bonsasus) is bovine tuberculosis, the pathogenesis of which in this species is not fully known. The aim of the study was to confirm a possible case of vertical transmission from a pregnant European bison with generalized tuberculosis to its 12-week-old foetus.

Material and Methods:
During the autopsy it was found that the bison had become pregnant, despite an advanced stage of tuberculosis. Material collected from the organs and foetus was placed on Lowenstein and Stonebrink media and incubated at 37 °C for 12 weeks.

Mycobacteria were isolated from the lungs and lymph nodes; however, the tissue of the foetus and fragments of the reproductive system were negative.

Vertical transmission was excluded, although it cannot be ruled out that infection could occur as pregnancy progresses.

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