Just keep taking him out he wont learn fcuk all sitting in all day, keep him tied up next to earth listening when your working the other terrier, that's if you have one ?
My terrier has been killing rats since day 1 & never had a problem , his nearly 8 now & has rats both ways mentioned .his never been jabbed either after his ratting sessions.
If anyone thinks this stuff is real then i recommend you reaching into your wife's/mom's ''Dildo draw'' & giving yourself about 12 hard WHACKS across the fore head
Then come back & let me know what you think