spine?

hey guys... im just wondering about my dogs spine. its sticking out. like i can kinda feel it. is he not eating enough? i brought him to the vet like 2 weeks ago and they never said anything, and i never really payed much attention to his spine sticking out. its not sticking out too much but i was just wondering if this is normal? i have a chow chow. his ribs are hard to notice, like i can feel the slightly if i really try hard to fell for them. but his spine is more noticable. he also doesn't eat when he's outside(usually) and if you remember from my previous posts about him gulping, he gulps. there was one night when he chewed every single piece of kibble tho. im not sure why. but i was rewarding him so much for doing it. but then the next day i guess he forgot. not sure. anyways... comments about spine or getting him to chew.