Why is this?
The only behavioural problem he has ever had was when he was a few months old and he would chew the sofa cushions because he wasn't allowed to sit on them. Nothing in his routine has changed whatsoever. They both have access to a completely fenced in back garden any time they want, so it's not like he can't go out. They have both been spayed/neutered. I am completely confused and at a loss as to how to correct this behaviour. Any ideas? Or maybe direct me to another place to ask?
ETA: Thank you all for your advice!
Do you have any dogs? Tell me about them! :)