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

This report documents clinical signs, semen parameters, and reproductive organ lesions in rams during a natural <i>Brucella ovis</i> outbreak. Eleven rams from 1 flock underwent 2 breeding soundness evaluations and necropsies. <i>Brucella ovis</i> was isolated from all semen ejaculates and confirmed <i>via</i> 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 <i>B. ovis</i>. Most were subclinical cases. Veterinary practitioners can utilize changes in semen quality and the presence of leukocytes as potential indicators of <i>B. ovis</i> infection in rams, which may prompt further confirmatory testing.