Brownie is 18 months old and until now has been sweet, cuddly and adorable. He lately has been showing very aggressive behavier, even to people he knows. He was given to me when he was 11 months old and until now welcomed all into the house (although with continual and annoying barking) but has started showing some unfriendly traits towards people, even those he's known since he came to us.
We have had little luck with 'accidents' even trying to schedule his outings very frequently during the day, but sometimes he will wait to come inside to do what he was outside for!
Any suggestions? All help will be appreciated!