Hello
If it's just the remotes you could try putting a dog repellent on it - like bitter apple (available at most pet stores) or make a concoction out of chilli pepper and water to put on the remote. If you apply bitter apple/chilli & water on a cloth first and then just rub down the remote, it won't harm the remote and the residue will be left behind to deter the dog.
Otherwise, the best way to keep your remotes in good health is to put them somewhere where he can't reach them
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What are you doing to help with his separation anxiety? What are his symptoms?
Blue