Food is a very important part of ensuring that pets lead healthy lives. However, their feeding behaviors vary, with dogs being omnivores or carnivorous omnivores, whereas cats are obligate carnivores, so meticulous attention must be paid to what they are fed. Today, one can get by without worrying about it too much, because optimized pet foods are readily available at supermarkets and convenience stores. However, fresh concerns have surfaced, as cases of metabolic syndrome are even being seen among cats and dogs. Just as with humans, we need the correct dietary knowledge to ensure that our precious pets can live long, healthy lives.