i just want to know how much dose it efect them when working because i have a paterdale x lakland x baorder terrier she has a undershock jaw. her mum and dad wher petty good woekers but i only use her for ratting and ferrting. shes a grate we dog hers a pic of her shes keen to go to ground as me and a couple of mates went ferreting for a couple of hours and as we stuck the ferret in we herd thumping and she got al exited and there was one pretty bit rabbit whole and and she went dwn and bk out but never been digging in my life so just want know if it is a big efect when working or what.