Most cat owners blame their pet’s saggy stomachs on snacks or spaying, but this belly flap plays a key role in feline anatomy.

Many cats have saggy bellies, even if they are not overweight. While some pet parents believe a swaying stomach is caused by incisions made during spaying or neutering, this lose-fitting skin is actually an important part of your cat’s anatomy.

Formally known as the primordial pouch, the feline belly flap is made of excess skin that runs the length of Kitty’s abdonmen and is most visible near his hind legs. All cats, regardless of their size or sex, have this fold, which serves several important purposes. First, the flap provides padding and protection during a fight, when cats may target each other’s vulnerable stomachs with their hind legs. Lose skin allows Kitty to break free when grabbed by an opponent or predator, making your pet’s pooch a fully functional part of his body. Kitty’s belly flap is more than a means of self-defense, however. The loose skin makes it easier for him to fully extend his body while running and aids in flexibility during other daily activities such as stretching and jumping. Researchers also believe this extra skin allows cats’ stomachs to expand when they score a big meal—an important consideration for your housecat’s wild counterparts that must hunt for their food. The size of your pet’s primordial pouch will vary according to his size, age, breed and weight. As a general rule, however, older and heavier cats have more pronounced pouches. This is a naturally occurring process as metabolism slows with age and your pet’s body begins to store excess fat. Cats that were once overweight and have shed the extra pounds also tend to have more pronounced belly flaps, as their skin stretches to accommodate excess weight. Though a saggy stomach is normal in cats, it is important to differentiate between the primordial pouch and obesity, which can harm your pet’s health. Because housecats do not need to hunt for their food, this is a common problem and one you should monitor. You can tell the difference between a primordial pouch and overweight stomach by watching your pet walk: The pouch will swing loosely and hang low, while fat stores tend to be firmer and closer to your pet’s frame. You should be able to feel your cat’s rib cage when you touch his sides, but his bones should not be visible beneath his fur. If Kitty is overweight, try adjusting his portions and engaging him in interactive play, such with a fishing pole, more regularly.

The primordial pouch is an important part of your pet’s anatomy that allows him to run, jump, stretch and eat in a natural way. By keeping your cat a healthy weight and adjusting his food and activity levels accordingly, you can help ensure he lives a long and healthy life.