| Popis: |
Disbudding prevents horn growth in calves through thermal or chemical cauterization and causes damage that is painful for weeks following the procedure. Current pain management strategies are only effective from 1 to 2 h (local anesthetic) to 1 to 3 d (nonsteroidal anti-inflammatory drugs). A potential practical solution for addressing longer-term pain may be to administer ethanol as a cornual nerve block. When administered at a high concentration, ethanol damages the functionality of peripheral nerves, promoting localized long-lasting analgesia. It is also thought to be painful, thus ethanol may be combined with lidocaine, as a mixed solution or administered beforehand. We tested the use of an ethanol cornual nerve block for anesthesia around the horn bud in 2 pilot studies. We used different concentrations and amounts of ethanol (100% and 70%) in combination with different ratios of lidocaine in our attempt to identify an effective block. In pilot 1, 14 nondisbudded calves were administered 2 to 4 mL of 100% ethanol below the bony ridge on each side of the head to block the cornual nerve at 3 to 10 d of age (n = 28 horn buds) and observed for 5 wk. The duration of loss of sensation was evaluated using pinprick tests 10 min, 1, 3, and 7 d after the block, and then weekly thereafter until 35 d or full sensation had returned. Pinprick tests consisted of lightly pressing a needle in 10 evenly spaced locations around the base of the horn bud (0 responses = no sensation, 1–5 responses = partial sensation, 6–10 responses = full sensation). Pilot 2 looked at the 24 h after the injection and consisted of 9 nondisbudded calves (5 mL of 2:1, 70% ethanol and 2% lidocaine per horn bud) and 6 disbudded individuals (5 mL of 100% ethanol, 70% ethanol, or 2% lidocaine per horn bud). All treatments were administered at the calf level. Anesthesia was checked 10 min after the injection and 4 or 16 h later. In pilot 1, on the day of the ethanol injection (0 d), there was no sensation in 85% of horn buds. Sensation began to return as early as 1 d after blocking, with only 50%, 21%, and 3% of horn buds having no sensation at 1, 7, and 35 d, respectively. Partial sensation was present in 25%, 17%, and 10% of horn buds at these time points. In pilot 2, 27.8% of horn buds in the nondisbudded group had no sensation, whereas 33.3% had partial sensation 10 min after the injection. In the disbudded calves 10 min after the injection, 100% of horn buds from the 100% ethanol group had partial sensation and 100% of horn buds administered 70% ethanol had full sensation. Four or sixteen hours later, 100% of horn buds had full sensation. Together, in these pilot studies, ethanol provided inconsistent anesthesia when used for a cornual nerve block. |
