Is there a need for vitamins other than for those C & K get from the wet food and dry food they eat? They eat Whiskas dry and wet food (they get a bit of wet food in the evening and morning) and Friskies dry food (we change the flavour when bag is empty so they don't have to eat same flavour again and again....So, any need for more vitamins?

Our vet isn't the best in the world and we can't get all information from him (if we want to know more, we have to pull the info out of him, and that's not nice I think!), but we are in a process of changing a vet. We had to take this vet because we don't have a car yet and he lives close by. But soon we'll have a car and we can go to this other vet who is immensely good (so my friend told me!). So, in the meanwhile, I ask this question from you guys.