Observations on the trajectory of the bullet in 15 horses euthanased by free bullet

The trajectories taken by the free bullets used to euthanase 15 horses were examined. The point of entry of the bullet relative to the recommended site was measured, together with the angle of the trajectory of the bullet relative to a tangent to its point of entry, the deviation of the trajectory from the midline of the brain, the structures of the brain that were damaged and the extent of this damage. Despite a reasonably consistent point of entry, there were wide variations in the damage inflicted, ranging from the total destruction of the hindbrain to injury to the cerebral cortex alone. The extent of the bullet's lateral deviation from the midline appeared to be the most significant factor affecting the level of destruction to the hindbrain, suggesting that angular direction may be more important than precise surface location in effecting a satisfactory kill.