Man walking 2 dogs at the start of book and a car pulls up

[Gareth]

This is driving me crazy! It’s about a man who used to be special ops I believe and the book starts out with him walking his 2 dogs and he notices a car following him. He ends up hiding out in some town living with a woman he met and some people show up to kill him but with his special skills he kills then both. I remember at the end of the book, he goes to get his 2 dogs back that he left with his sister…. Pretty vague but it was a great book . HELP!!!