A single, episodic event of unilateral/bilateral scrotal swelling in a group of adult boars at an Austrian boar stud

Background Scrotal swelling is a clinical situation which can be caused by different aetiologies. In this case report, we describe a multi-week episode of unilateral and bilateral scrotal swelling in boars at an Austrian boar stud and its diagnostic work-up. Case presentation In the summer of 2020, the herd veterinarian of an Austrian boar stud reported that over a period of six weeks, five out of 70 boars presented with unilateral severe swelling of the left scrotum and three out of 70 boars with bilateral severe swelling of the left and moderate swelling of the right scrotum, respectively. A complete history was obtained and an on-site evaluation of the facility was done. Five boars were necropsied, and a variety of samples harvested for further diagnostic investigations. Infectious differential diagnoses associated with unilateral swelling of the scrotum or the testis were excluded through serological and tissue testing. In three of the five boars, histopathology revealed complete acute haemorrhagic necrosis of the left testis concurrent with strongly congested blood vessels. Review of the collected information with a group of experts in the field of boar stud management resulted with consensus that, most likely, trauma was the etiologic event causing the clinical signs and pathology. Coincident with discussion of implementing video recording cameras in the boar housing area, no further clinical cases followed. As this case occurred during the first lockdown of the COVID-19 pandemic, we propose that the distress and travelling restrictions may have contributed to frustration among boar stud workers, which was consequently expressed as misbehaviour against boars. Conclusions Once all known infectious causes of unilateral swelling of the scrotum were excluded, a critical diagnostic work-up focused on non-infectious causes. Non-infectious causes, such as trauma, need to be carefully evaluated, as it may also include human misbehaviour against boars. Summarizing all findings of this case report, the authors hypothesize that a blunt trauma was the reason for the series of mainly unilateral swelling of the scrota of boars.