Fast acting, nerve block local anaesthetics are well recognised as effective agents for relieving the acute (ischemic) pain experienced by lambs in the first hour after being ringed. Thus the Numnuts animal behavioural science studies investigated the response and effectiveness of our system at dispensing a ring and a local anaesthetic in a single device that is simple, quick, safe and easy for the farmer to use. We expect the results to be published in a peer reviewed journal during 2018. A poster and summary of the results presented at the International Sheep Veterinary Conference in Harrogate May 2017 can be downloaded here.
Signs of acute pain and changes in behaviour occur for 60 to 90 minutes following castration and tail docking with rubber rings, the husbandry practice called marking. For many years, vets have used local anaesthetic to reduce this pain. Efficacy of the Numnuts tool to alleviate pain by injection of local anaesthetic when the ring is applied has been studied in field trials by CSIRO in Australia and in pen trials by Moredun Research Institute in Scotland. During development of the Numnuts tool more than 1000 lambs have been studied.
The trials compared pain behaviours in three groups of lambs:
1) Numnuts (rubber ring and local anaesthetic applied by Numnuts tool)
2) Ring (rubber ring applied by conventional elastrator tool)
3) Sham (lambs handled but not marked).
Female lambs were tail docked and male lambs were castrated and tail docked. Lambs were placed in a traditional Australian lamb cradle for marking. To avoid biases, behaviours were scored by scientists “blinded” to the treatment each lamb received.
“The number of pain behaviours was reduced by up to 68% in Numnuts lambs in comparison to Ring lambs”
Numnuts lambs were noticeably more relaxed than Ring lambs when released from the cradle. For the next 20 to 30 minutes, when pain is most intense, the number of pain behaviours was reduced by up to 68% in Numnuts lambs in comparison to Ring lambs. Similar benefits were seen in male and female lambs. At subsequent time points, the number of pain related behaviours were low in all lambs, and differences between Numnuts and Ring lambs were less noticeable.
Numnuts does not abolish all the pain associated with marking in comparison with Sham lambs. Similarly, for humans, dental procedures like fillings and tooth extractions performed after injection of local anaesthetic are rarely pain free.
Numnuts provides a major advance in the control of pain associated with ring marking in lambs. Benefits in mothering up, ease with which the mob of sheep can be movement to grazing pastures after marking, and growth rates will be examined in subsequent trials.