The fat makes sure they won’t get as wet in the rain, won’t get dust all the way into their skin, and won’t get their fur mangled and damaged. It also keeps the skin soft. The coat has elasticity and a sleek top layer, making it soft and not mangled without split ends.
Without extra sebum in their coat, their coat can fluff out in the air and be lighter even though its heavier.
This is the dense fur, flat hair strands, coat hairs that seem light, can stand out from the body of the animal, are movable, not too heavy, not too oily, don’t have a systematic characteristic of undercoat, the hair rejects water, but the coat is more prone to dryness than being moist.