Try bones and toys to keep him busy , I had the something after a while she stop putting everything in her mouth, but not before she eat a frog lol and I had to rush to the vet , just so the vet could tell her she was a pig Lol !
I agree do the gate thing for a while , and when not at home , they'r like baby's everything in the mouth, they grow out of it.
enjoy your furbaby !
bark@ulater!!!
manina,miley

,max