Mature dog has suddenly begun destructive chewing.

I have 3 dogs – all older. 1 is 7.5 years old. I haven’t never had an issue with any dogs destructive chewing and have not needed to crate train.

About 8 months ago, my 7.5 year old began chewing destructively every once in a while we left the home, even for short periods, which has never been an issue.

Over the past 8 months i have attempted what i believe is every imaginable solution. Increased stimulation, tons of toys and chew devices while gone (he does not touch them at all), crates – with slow introduction (he has destroyed every type, including gunner, or harmed himself attempting to do so). It doesn’t matter if i leave for 30 min or 5 hours, he chews. And he only chews things that he believes will get him out of the house (doors, trim, etc).

I have resorted to putting all 3 dogs in a spare bedroom while gone, to avoid continued thousands of dollars in damages to my home. I put a metal plate on the door, because he almost chewed all the way through the first one. He is now metal plating and filing down his teeth from trying to chew it.

Obviously, none of this can be good for him, or me. What in the world could be happening and how can i help him?