The effects of diarrhoea, tail length and sex on the incidence of breech strike in modified mulesed Merino sheep.

Merino sheep were treated with purgative to induce scouring and the effects of tail length and sex on the incidence and origin of breech strike were examined. In sheep treated with the modified Mules operation, those with tails docked very short were strongly predisposed to tail strike, and to a lesser extent, crutch strike. Tails docked level with, or just below, the tip of the vulva in ewes, and at the equivalent length in wethers, were struck far less frequently. Within each tail length group, wethers tended to be more susceptible than ewes. L. cuprina was the principal species of fly involved in strikes, although the presence of L. sericata and C. augur was conspicuous.