Semen quality and pathological lesions in rams naturally infected with Brucella ovis during an outbreak in Saskatchewan.

This report documents clinical signs, semen parameters, and reproductive organ lesions in rams during a natural Brucella ovis outbreak. Eleven rams from 1 flock underwent 2 breeding soundness evaluations and necropsies. Brucella ovis was isolated from all semen ejaculates and confirmed via whole-genome sequencing. Despite above-threshold scrotal circumferences, all rams were categorized as unsatisfactory due to poor semen quality and leukocytes in semen. Semen motility values in 9 of 11 infected rams and morphologically normal sperm in all infected rams were below the recommended threshold values. Necropsies revealed gross lesions in 7 of 11 rams, with histopathology revealing inflammatory lesions in the epididymides, ductus deferens, ampullae, and seminal vesicles in all rams and in the testes in 9 of 11 rams. Inflammatory infiltrates were primarily lymphoplasmacytic and neutrophilic, with fibrosis, vasculitis, mineralization, and spermatic granulomas also observed. Key clinical message: Gross and histopathological lesions as well as semen characteristics were described in rams naturally infected with B. ovis. Most were subclinical cases. Veterinary practitioners can utilize changes in semen quality and the presence of leukocytes as potential indicators of B. ovis infection in rams, which may prompt further confirmatory testing.