You might try fish oil. I cut open fish oil capsules and put it in my kitties and doggies food. The dogs will just eat the capsules, the kitties perfer it squeezed over the food.

It does wonders for their coats. And has obvious health benefits.

As far as food...Science diet is not a great food, Mine are on Royal Canin indoor formula and do great on it. Wellness is another quality food for both cats and dogs.