Technique for Cornual Nerve Block - Cornell University



Technique for Cornual Nerve BlockWear gloves if desired.Restrain 5 calves using halters.Locate the groove parallel to the temporal line alongside the forehead of the calf running between the lateral canthus of the eye and the horn bud. Draw up 8cc 2% lidocaine in a 12 cc syringe. With a 20g x 1” needle attached to the syringe, insert the needle in the depression parallel to the temporal line pointed towards the horn bud. The needle is inserted just rostral to the midway point between the eye and the horn bud. The tip of the needle should end up at the midway point. Bury the needle to the hub so that it does not pull out easily when the calf moves. Aspirate and if not in a blood vessel, inject half of the lidocaine (4cc) subcutaneously around the cornual nerve. “Fan” the needle while injecting if necessary. To reposition the needle, pull out about ? inch before redirecting and reinserting the needle. Aspirate again before injecting. If the needle bends, replace it before continuing. (If aspiration is used to avoid intravenous injections, do not use the same syringe for another calf in order to prevent bovine leukemia virus transmission.) Using the remaining 4cc of lidocaine, follow the same procedure for the opposite horn.Allow 3-5 minutes for the lidocaine to take effect before dehorning. Due to anatomical variation, occasionally the nerve block is not effective. If you find this is the case, attempt the block once more. Please ask for assistance from a clinician if you are unable to properly anesthetize your calf’s horn bud after the second attempt. Technique for epidural block Locate the groove between the last lumbar vertebrae and the first coccideal vertebrae by moving the base of the tail up and down and using your index finger to palpate the groove. After the intervertebral space is located insert a 18 gauge needle into the groove.Inject 3 ml of lidocaine into the intervertetebral space.The procedure should be repeated for all 5 restrained calves before the tail docking procedures are performed. Technique for thermal dehorningAfter performing blockPreheat the dehorning iron.Wear gloves if desired.Clip the hair over each horn bud.Straddle calf between your legs, holding her head to the side between your thigh and your non-dominant arm. Hold the calf’s ear out of the way if necessary.Place the tip of the burner over the horn bud, apply pressure, and rotate the dehorner by twisting your wrist. The entire horn bud must fit in the diameter of the dehorner. Ask for help from a clinician if that is not true for the calf you are dehorning.Continue the application of heat for 10 to 15 seconds until there is a break in the skin around the horn bud.Lower the dehorning iron handle and scoop out the horn bud. Drug withholding times: Dairy heifers rarely are sold for beef at a young age, but to follow extra-label drug use laws, the owner should be advised that meat withholding times should be observed for this extra-label use of lidocaine and flunixin meglumine. The lidocaine meat withholding time is 1 day for meat (90 days for organic production) and oral flunixin meglumine has an 8 day meat withholding (extra-label use of flunixin meglumine, including oral administration, is not approved for organic production). ................
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