My Chiwawa Is 6 Mths Old And Keeps Eating Cat Ka Ka!!! What Cause This?

DJ is 6 mths old and will not quit eating the cat ka ka that the neighbors cats keep leaving in my yard. They are all sick and they dont even bury it. Someone said that it means they are lacking something in there diet. He also will hardly ever eat his dog food. And when we eat he acts like he his starving.