Prevalence of ballooning of the severed carotid arteries at slaughter in cattle, calves and sheep.

Previous work in calves indicated that ballooning of the severed arteries is a potential concern in animals receiving a reversible stun before slaughter, and in animals not stunned before slaughter, as it could extend the duration of brain function before the animals die. This study determined the prevalence of ballooning of the carotid arteries in a total of 987 cattle, calves and lambs at slaughter. The severed ends of the carotid arteries were examined by palpation. The prevalence of ballooning that was 3cm or more in diameter, was 16%, 25% and 0% for cattle, calves and lambs, respectively. Artery sections were taken from a sample of large cattle and examined histologically. In ballooned arteries there was coagulated blood between the outer surface of the artery and the inner aspect of the connective tissue sheath surrounding the artery, suggesting the formation of a false aneurysm in the ballooning phenomenon.