What kind of tinned food and mixer are you using? Plus what ratio are you using. We feed ours FROMM kibble and Henri gets about 3/4 cup of dry and about two spoon fulls of canned. The females get a little less. On a growing pup, I would rather give too much food as not enough. If he starts to get a little chubby, then cut back just a bit so he maintains a good figure. You should never be able to see ribs, but can feel them with firm pressure.