The recommendation is just that-a recommendation, not the amount you must feed. Gaining 4 lbs in one week IS NOT healthy, even for a dog that needs to gain weight, and especially not for a large breed dog. Weight gain should be slow and steady. She may end up needing 3 cups a day, but probably not while she is having diarrhea issues and you may need to build her up to that amount slowly, so her body can get used to having that much nutrition at once. She may need her food in 3 meals at this point so they can be smaller meals. At this age, you should be able to see her last ribs and her hip bones and about 3 vertebra. Don’t worry about her being skinny, that can wait until the stool issue is fixed, as long as she isn’t loosing a bunch more weight.
