How much food should you give a chihuahua?

It depends on what breed it is. Some will eat anything you give them and therefore overeat. This habit can develope by you only serving your pet specific portions and nothing more until the next schedualed mealtime. This puts your dog in a habit of eating all it is given. If your dog won't overeat then i suggest leaving out a bowl of food all the time. If your dog will, I suggest talking to your vet. He will factor in the breed and size/weight to help you.