My yorkie is about 1 1/2 years old and he has been a pickey eater since we got him. He seams to get sick of the food and treats i get him verry quickly, he eats canned and dry food, he has access to dry food all the time but he seems to only eat when someone is in the room with him. He is about 6lbs but he seems thin, is this normal ? What can i do.