nnbreeder is correct..the skin shot goes in the back of the neck..pinch up the loose skin.
just be careful you don't poke thru.
muscle shot goes in the meaty part of the breast..
sometimes you can pinch the skin there for a skin shot..but can sometimes that makes a "bubble" under the skin..
do it on the opposite side of the crop if you're doing the breast.
good luck..
hope they recover..