3 products which yes basiclally do the same thing Spotinor / spot-on a 5ml standard dose for sheep which applied in one place ,middle of the front shoulders is absorbed into the skin layer and spreads over all the body and lasts for up to 6 weeks , the tick has to bite to take in the chemical to kill it . Crovect which is applied as a pin stream from the crown to the rump along the spine in amounts that vary according to the sheeps weight and then spreads in the sheep grease all over ,lasts for up to 10wks . Dysect works similar to crovect just different amounts and slightly different application . Barrier produces a natural tick repellent and tea tree /citronella are said to repel ticks but have to be constantly reapplied