I have black sheperd that is a one year and half. I feed her a good sports or work dog food 6 cups a day. She just can't gain weight . She is very active on five acres. People actully ask me what is wrong with her.

Has she been checked for intestinal parasites? If not that may be a place to start. You should be able to take a stool sample in to your regular vet for testing, there are all sorts of things that survive in the soil just waitng for the opportunity to be picked up by a host that is just passing by.

First, I would not go off what people say. When a dog is in good condition, people will assume the are too thin.

What does your vet say about her weight? Does he/she think she is underweight?

If she is considered to be underweight, you can always give her a supplement to help with her weight gain. Satin Balls are very high in protein and fats and carbs. They are typically used for skinny, sick dogs. Extremely active dogs can benefit from these as well... I've attached the recipe How to Make Satin Balls | eHow.com

Please make sure that your dog is indeed underweight. Have a vet examine her and determine if she is underweight. Obese dogs aren't healthy, and you don't want to see your beautiful dog become overweight.

She could also be hyperthyroid. Hyperthyroid dogs will inhale food and not gain an ounce. I've attached a webpage that talks about hyperthyroid and some of the symptoms that you may notice.. Excess Thyroid Hormone in Dogs | petMD

Hope I helped!

It could be that the food you are giving her doesn't have the nutrients she needs. Sheperds a large dog, she might need a large breed food.