I have an active 14 month old female doberman. She eats all the time, but doesn't seem to gain weight. You can see her ribs and spine through her coat. She's very active and happy, but just doesn't seem to gain weight. Is it normal for a doberman to be this skinny. If not, any recommendations on what to feed her to bulk her up. I am a first time doberman owner and need to find out more information. Thank You.