What is a down coat on a cat?
Every cat, regardless of the length of his fur, has three layers of hair. The top layer is the guard coat, the secondary layer is called the awn, and the soft layer just against the skin is called the down.
It’s not a bad analogy to think of the down as the cat’s thermal underwear. These hairs are soft and wavy, and provide an important layer of insulation against the cold.
It is actually at this lower, thicker level that cat hair will mat, because the longer upper hairs become enmeshed with the down in a painful tangle. Effectively grooming a cat means working through all three layers of the fur to remove excess hair. Special combs or rakes can be purchased that will reach into the down fur without yanking or pulling, which not only hurts, but will make him resistant to being handled.
Outdoor cats or cats who go in and out will react to seasonal changes in temperature and shed their undercoat. This is why outdoor cats often look “scraggly” in the spring and summer months, with patches of skin visible through the fur.
Inside cats are less prone to react seasonally and will often keep their undercoat year round, especially if their owners like to keep the air conditioning going. It is also possible that these cats will simply shed year round as well.