Impact of carotid artery sectioning on cerebral blood flow in bovines: a numerical hemodynamic study

Objective To investigate the hemodynamic consequences of carotid sectioning, as performed in religious slaughter, on cerebral blood flow (CBF) and pressure in cattle. Religious slaughter typically does not allow preslaughter stunning, which has led to scrutiny over concerns that blood flow from intact vertebral arteries or vascular occlusions could delay loss of consciousness and potentially result in unnecessary pain and suffering. Methods A numerical model of the bovine cerebrovascular system was developed using COMSOL Multiphysics, incorporating anatomical and physiological parameters. Simulations were conducted across pre, immediate, and postcarotid sectioning states and scenarios involving vessel occlusions. Results The simulation revealed a near-instantaneous loss of approximately 99% of CBF and pressure immediately following carotid sectioning. Vertebral artery flow is redirected away from the brain, via the vertebral-occipital anastomosis, toward the severed carotids. Simulated carotid occlusions did not meaningfully alter cerebral hemodynamics or delay the loss of blood flow and pressure. Conclusions Carotid sectioning causes an almost complete and immediate cessation of cerebral perfusion, with vertebral artery flow and carotid occlusions exerting negligible influence. The results support the conclusion that religious slaughter methods, such as shechita and halal, in which the major blood vessels are severed, induce rapid loss of CBF and pressure and therefore rapid loss of consciousness. Clinical Relevance This work underscores the value of numerical modeling in providing objective insights into the hemodynamics of religious slaughter without causing undue harm to any animals and confirms prior findings of a precipitous drop in blood pressure and flow following the incision.