Q. Can I feed my cat food that contains in its ingredients meat even of chickens and milk ingredients together?
A. The prohibition of eating meat and milk together is based on the Torah command: "Do not cook a kid in its mother's milk" (Exodus 23:19). Not only is the eating of meat and milk in combination prohibited but as the pasuk quoted mentions even the act of cooking them together is prohibited, as well as deriving benefit from such a mixture.
As a safeguard, the Sages disallow the eating of meat and dairy products at the same meal, or preparing them with the same utensils. Therefore, a kosher kitchen must have two separate sets of pots, pans, plates and silverware – one for meat/poultry and the other for dairy foods.
On question 64 regarding if a nurse serve a non Jewish patient meals that contain cooked meat and milk, we wrote: “Horav Shlomo Miller’s Shlit”a opinion is that it is permitted in need only, since there are several “Sfeikos” or doubts as to the nature of the prohibition in most common cases. Probably only a Rabbinical prohibition of Basar Vehalav is involved. The preparation may not entail the required act of Bishul or cooking proscribed by Halocho. There is also doubt as to what kind of meat and milk is being used and the amounts involved. All the above will create a ‘Sfeik Sfeiko’ or double doubt condition, which albeit still prohibited for consumption, would render the meal permitted for benefit.”
Rabbi A. Bartfeld as revised by Horav Shlomo Miller, Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a.