Be careful careful with nutrical- it can supress the appetite and cause them to not eat like they should. I would recommend purchasing some canned food that she loves, and use that a few times a day in between her normal kibble. Just a thought.
And like other have said, don't be mad at your vet for recommending Science Diet, it's what they are taught and they make easy money selling it. Do your own research and made your own educated decisions. We as pet owners have to advocate for our animal's health. I am not saying that we shouldn't take our vet's advice, it's just that our animals are more important to us, then them. And yes, money is a big part of their agenda. The good ones care about the animals, but money is still a huge factor. I can vet bash cuz I'm married to one
