All sheep shown at 4-H Youth shows should be docked in a manner that does not compromise the animal’s health and well-being. As a working guideline we recommend that lambs be docked so that at the show the tail (dock) is long enough to be lifted. Moreover, the stress caused by docking increases with age, therefore docking should be performed early in life and certainly before the lambs are two weeks of age. The tail should be healed at the time of show and any animal that has been re-docked, except for a medically justified reason, should be ineligible for show.
From “Tail Docking Policy Link” on the WSU 4-H Sheep Additional Project Information Page.