Do dogs go through stages of teething? Our guy teethed at the usual 6-8mths. Nothing has changed in our daily routines, plenty of walks and stimulation. Now at 10mths we've caught him biting on chairs on more than 1 ocassion. He's never done this before. And it was a curious bite but an extensive chewing (he was left unattended for 5 minutes as I was in the washroom).