my labrador who i have had for 3 years has recently started to act aggressive. i got another dog earlier this year which he is fine with but my sister got a pug recently and she leaves him at my house during the day and my labrador acts very aggressive towards him, growling and snapping everytime he comes near him, and today my neice who is the pugs "mum" sat near my lab and he snapped at her and shes only 7, he also snapped at me earlier today