Good question for the Vet. I'm not familiar with the fish & sweet potato variety. I look first at a food to make sure its grain-free, and then I look at the other ingredients. The fewer ingredients the better for pets with allergy issues. I started giving my dogs and cats "Fresh Factors" by Springtime Inc. (just throw on top of food for dogs, for cats, crush up with back of spoon and mix in with wet food ) and it seems to make everyone noticebly more energetic/healthier. (My 17.5 year old cats used to sleep 24/7, now they are going outside, running around the house, chasing each other, etc...) I had ordered it originally for my older spayed female dog who started leaking- I had been told this occurence was common for older spayed dogs, but also told there might be something lacking in her diet. Whatever, the leaking went away since I've been giving the Fresh Factors. Fish Oil is always an excellent supplement to throw in as well. An excellent all-in-one supplement I use comes in powder form, (mix it in with wet food)- its made by 4Life, and its called "Transfer Factor,Canine Complete - a bit spendy, but if your dog has any potential health issues at all, this stuff goes a long way in keeping a dog in optimal health/strengthened immune system.
I've had my Schnauzer on the fish & sweet potato for months now. It really is helping with her allergies, but do you know if she needs to take supplement vitamins with this food ? The reason I ask is she has been doing strange things like .....eating the soil in my potted plants. She has a really great Vet and I will ask him about this , but I was wondering if anyone else has had this experience ?