My 2 1/2 yr old GSD is only 77 lbs...we have been feeding him 4 cups of Petcurean Go Salmon a day with 1/4 cup of Tripe on top. He is energetic and happy but he seems to be so underweight...you can feel his spine and hip bones, but it is disguised by his long coat. We have increased his food to 5 cups but have not seen any weight gain. We have to be selective about what we feed him because his skin gets really itchy. We were told he has yeast allergies, so he can't have anything that produces sugars. To be honest his skin is better since putting him on a limited diet, but it is not great...he still has some dandruff next to the skin and it itchy. His coat however looks silky and great. It's very confusing, but if someone could give me any insight or suggestions it would be greatly appreciated. Thanks!