Eh, maybe? There's got to be _something_ for sociopathic ex-squaddies to do who don't want to go back to civvie street. I found their existence believable, if not the high speed Range Rover driving stuff. It's very clearly not going for full-on realism, obviously a fantasy spy show. So the dogs work in that context - at least for me.

EDIT: someone else mentioned Tinker Tailor (either the '80s BBC miniseries or the Gary Oldman movie - once again he's killing it) which is far more grounded. That might be more up your street? I enjoyed both a lot. Bleak as hell though.