Electro-immobilisation of sheep may not reduce the aversiveness of a painful treatment

Sheep were repeatedly chased down a race and were then either subjected to the noise of a shearing handpiece or had wool shaved off. An increase in the time that had to be spent pushing the sheep down the race indicated that the latter treatment was aversive. Similar results were obtained when the sheep were subjected to the same two treatments while electro-immobilised. This throws doubt on the analgesic effectiveness of electro-immobilisation.