I have a cat with some rather peculiar tastes. He's about two years old,
rather skinny (the runt of a litter, actually), and has a fairly normal
appetite. Sort of. You see, he won't even sniff the cat food we leave for
him to eat, when he comes in the house. He walks right by it, and proceeds
to rob food from the dish belonging to our 10-year-old golden retriever. If
the dog food bowl is empty, he'll sit by it and yowl until someone fills it
up. I always give in, not seeing any harm in it, but I was just curious as
to whether or not this is really a good idea. If not, how do I go about
curbing him of this unusual preference?
 I think the reason he likes dog food, is because I would sometimes feed it
to him as a kitten. Back then, he and three siblings were strays that we
would feed outside. If the cat food ran out, we would give them dog food in
the meantime. Eventually the other cats ran off to unknown places, but this
one stayed and made quite a pet of himself. He now goes in and out of the
house at will, sometimes staying inside for several hours to sleep. He ate
cat food regularly for quite a while, but over the last few months he seems
to have lost his appetite for it.
 Any ideas?