Puppy fur is made up of individual hairs. The character of a puppy coat depends on the texture and color of individual thread-like structures made of keratin that grows outward from hair follicles in the skin.
What Is Fur?
Fur serves as a protective barrier that shields the puppy’s skin from the elements, regulates body temperature, and protects puppies from sunburn, heatstroke, frostbite, and hypothermia. Hair also acts like a candle "wick" to route scent-chemicals related to identification and sexual status, sending scent from the skin into the air.
All healthy dogs have fur, but the amount and type of hair coat varies in individuals and from breed to breed. Even the hairless Chinese Crested dog has hair on the face, feet, and tail.
What Is Hair?
Hairs are composed of the hair shaft, which is the visible portion of the hair, and a root generated by a hair follicle within the skin. Dogs have compound follicles, which means as many as 20 hairs can grow from a single pore. People have simple follicles which produce only one hair for each pore.
Dogs have three kinds of hairs, characterized by length and diameter. Guard or primary hairs are the longest, coarsest hairs of the outer coat. Secondary hairs of various lengths make up the undercoat. Medium length awn hairs make up the intermediate coat, and the undercoat is soft, short cotton-like fur that's curly or crimped. All three types may sprout from a single compound follicle.
The length of the hair shaft and the ratio of guard to undercoat hairs varies from breed to breed. When the hair follicle that produces the hair is slightly twisted, the hair that grows is curly. These differences, as well as a variety of colors and patterns, produce each dog's distinctive coat.
How Fur Grows
Each hair grows from the root outward in a cycle of rapid growth called anagen; shrinkage called catagen in which the root detaches from the follicle, and a resting period termed telogen. Old loose hairs in the telogen phase are pushed out—called shedding—by new hairs as the anagen cycle begins. Shed fur is composed of telogen hairs.
A single human hair may grow for up to six years before being shed and replaced by a new one. The growth cycle of your puppy’s hair is much shorter and more synchronized, which accounts for the massive shed. Fur growth cycle averages about 130 days, though this varies from breed to breed. The exception is the so-called "non-shedding" breeds like the Poodle and some terriers, whose coats actually grow for several years before being replaced.
A healthy coat is possible only with proper nutrition because hair is 95% protein. Your puppy's coat retains its healthy glow from the proper balance of fats and other nutrients. Poor nutrition is first reflected in the skin and hair coat by dry, lifeless fur or abnormal hair loss. Grooming is beneficial for all dogs and particularly important for dogs with thick long coats.
Whiskers are the thick, long, wire-like hairs that protrude from the dog's face. Also called vibrissae or sinus hairs, whiskers are specialized hairs that are long, supple and thick; they may also appear as groupings of short stiff bristles.
Whiskers are much more developed in animals that hunt during the night or low-light times. They act as feelers and are seated deep in the skin where they trigger nerve receptors at the slightest touch.
Dogs have whiskers in four places on each side of the head and two on the lower jaw. The most obvious are those on each side of the dog's muzzle, where whiskers grow in four rows; they provide information when the dog is sticking his nose in and around objects.
Bristles of four to five whiskers above each eye act like extended eyelashes. They prompt a protective blink reflex if touched. A clump of whiskers is located on each cheek and a smaller one near each corner of the mouth. Lastly, the dog has a tuft beneath the chin, which probably serves to keep his head from scraping the ground during tracking behavior, or may even help puppies in food-burying activities.