Buy him a KONG brand "BALL",
Watch out for the Kong starting to get torn up....years ago, one of my Nealoptan Mastiffs ate a Kong and had to have surgery to remove it...3 liter Coke bottles were another of his favorite chew toys, especially after the Coke started leaking out.
"Nealoptan"
...Neapolitan...I guess I had better get some sleep.
Neapolitans are so great--a friend of our has one. Their house was broken into while they were gone, once, and they came home to find the place a wreck, the door standing wide open, the burglar up a tree outside, and the Neapolitan at the base of the tree, keeping watch.
They let the guy stay up there, while they called the police.