Aerobic oxygen is also great. You get it at health food stores for humans. Just check the dosage with your vet, or the store clerk(one who knows their stuff).

I once house sat two black labs. The dose was 20 drops a day in the water bowl. It was fine for the other dog.

For the old arthritic dog, it really made a difference. She got more playful, though was stiff. But definitely happier and more comfortable.

Good luck with Louie!