The use of an acoustic device to identify the epidural space in cattle

Twelve healthy cattle (weighing 188-835 kg) were placed in stocks and sedated with xylazine. Caudal epidural puncture was performed using an acoustic device that indicated a decrease in resistance with a change in pitch. Lidocaine was injected to verify correct needle placement by assessing needle prick stimuli applied on the left and right side of the tail root and the perineal region, and the loss of tail and anal sphincter tone. Pressure measurements were recorded during penetration of the different tissue layers and in the epidural space. A clear and sudden decrease in the pitch of the acoustic signal was audible in all 12 cattle. All cows showed clinical effects indicating successful epidural anaesthesia. The pressure in the epidural space after puncture was -19±10 mm Hg. The device may be of assistance in identifying the epidural space in cattle.