Arrested blood flow during false aneurysm formation in the carotid arteries of cattle slaughtered with and without stunning

The time to onset of arrested blood flow and the size of false aneurysms in the severed carotid arteries were assessed in 126 cattle during halal slaughter without stunning. Thirty six cattle (29%) showed early arrest of blood flow. In 6%, both the left and right carotid arteries in the same animal stopped bleeding before 60 s had elapsed following the neck cut. The time to early arrested blood flow was on average 21 s, and this was accompanied by enlargement with false aneurysms which occluded the arteries. In the arteries which were still bleeding at 60 s after the neck was cut the artery size was normal. Based on comparative data from different slaughter premises it appeared that making the cut in the neck at the first cervical vertebra instead of the second to fourth cervical vertebrae reduced the frequency of false aneurysm formation and early arrested blood flow. This was confirmed in a separate controlled trial where 100 cattle were stunned with a captive bolt and the arteries were examined following neck cutting at either the C1 or C3 positions.

► Some cattle lose consciousness slowly when slaughtered without stunning. ► This is because blood flow is arrested by false aneurysms in the severed arteries. ► Cutting arteries at the C1 position in the neck reduces the frequency of this problem.