Cats are obligate carnivores. That means they can and should subsist entirely on a diet of meat. Their systems are designed to obtain all needed nutrients as well as water from a meat-only diet. We fed our cats dry food only at one point and one of them often seemed sick. After we switched to wet food she perked right up. When we are gone for a couple of days and we leave dry food out for our cats they drink a lot more water because they are not getting it from their diet. But that is not natural or healthy for them, and they routinely thrive on canned kitty food. I would encourage an all-meat diet for your cats when you are there to provide it.