SQ...never deviate from manufacturers suggestion unless a vet tells you to do so...there are differences other than speed of delivery. Such as pain, abcess, etc...Ivermectic BURNS, and while I am not sure about the specific reasons ivermectin is administered SQ a lot of SQ drugs have a much higher risk of abcess IM than they do SQ...plus on any meat type animal you should really try to avoid IM injections because of meat quality.