I had a chow "Special" years ago who was 11. She quit eating... My vet ended up sending her to a vet school nearby that did a sonogram and a biopsy.. It ended up that she had stomach cancer .. a rather large tumor and this caused her to feel full and not want to eat. I fed her baby food and boiled chicken. She lived for probably another 5 months.
Hopefully, that will not end up being the problem for your baby. If your vet hasn't done xrays or blood work... I'd try another vet. Or ask your vet to do it. Maybe he has a blockage... I know there are some breeds that get their intestines twisted inside somehow.....
Let us know... Hope it goes well and he gets better.. I think Chows are prone to stomach cancer... ask you vet to check him for that.
Also, you can ask your vet about giving him pepcid ac. My vet recommends this when my dog gets into junk in the country.
2 Dogs- Frisbee (lost Frisbee 7/31/12 age 14
3 African Greys-Max, Sammy, and Magic
4 Chinchillas- Freckles, Curly, Buddy, Baby
5 Bettas- LuckyBlue, LittleBlue, Nebula, Ember and Anderson