Our big boy, a Bernese Mountain Dog, 8.5yrs old, has had arthritis for a year, which has now been identified on X-ray as severe 
He hasn't eaten properly for a week. Just a few tit bits. Vet seems to think he'll be ok once we've put him on complete rest, but he's so unhappy. And he's wasting away before our eyes.
He keeps falling over and the last 2 days has started whimpering whilst just lying down.
I think our vet is happy for him to continue as long as we are buying the monthly expensive arthritis medicine, but I can't let him go on like this, can I?
Advice much appreciated. Thanks all.