Skin and Coat
Skin
The skin is the largest and
one of the most important organs of the body. It forms a barrier to protect
the body of the dog from infections, parasites, and the elements. It also
maintains the body's internal environment, preventing loss of moisture and
other body constituents. Because the skin is on the outside of the body, it is
easily exposed to outside elements and is susceptible to injury and disease. It
is also very visible, and disorders are readily detected during an examination,
so your groomer should know how to perform an examination and let you know if
they have spotted anything unusual.
Hair types
Puppies are not born naked.
Their skin is covered by a short, soft, and sometimes woolly-like hair.
Sometimes the puppy hair, or fur as it is sometimes referred to, is a similar
color to what is expected as an adult. Sometimes the puppy fur is slightly
lighter when first born. For instance, Dalmatian puppies are born with few or
no black spots. The coat is pure white with the black spots developing as the
puppy grows.
Most puppies of all breeds
develop a coarser, longer, and occasionally darker coat by six to eight months
of age. Breeds and individuals have different rate of coat development. Factors
such as day length, hormones, average outdoor temperature, and nutrition may
influence coat development as well.
Dogs have two types of hair
in their coats. There are short fluffy hairs called secondary hairs. Other names
for secondary hairs include under-fur and undercoat. The second type of hair is
the longer and stiffer outer hairs called primary hairs. Primary hairs are also
referred to as guard hairs, outer hairs, or outer coat. Dogs also have a third
type of hair: the whisker. Whiskers are called tactile hairs because they help
the dog sense his surroundings.
Even though all dogs have the
shorter secondary hairs and longer primary hairs, the ratio differs by age and
breed. Newborn puppies lack primary hairs. That is why their coats are short
and soft. Usually by six months of age most puppies have developed a good
growth of primary hairs so their hair coats are longer and coarser. Many
variations exist amongst breeds as to the exact length, color, and texture of
the hair coat. These coat differences are largely the result of the ratio of
primary to secondary hairs and the texture of these individual hairs.
Each hair grows from a simple
opening within the skin called a hair follicle. A puppy is born with all of the
hair follicles it will ever possess. Any future differences or changes of the
hair coat will be due to changes within the follicle. Each hair shaft produced
by a hair follicle will eventually die and be removed (shed) and replaced by a
new hair shaft produced by that hair follicle. All dogs of every breed
continually shed old dead hair from the follicle and replace it with a new live
and growing hair. There is no such thing as a non-shedding breed. The
extent or rapidity to which an individual sheds is, however, governed by such
factors as age, amount of sunlight, outside temperature, breed, sex, hormones,
allergies, nutrition, etc. It is important to note that curly coated breeds
will often appear non-shedding only because the dead coat gets trapped in the
curls instead of falling off. These breeds will matt more easily and
therefore needs more frequent grooming.
Breeds and individuals within
every breed will shed and regrow hair at varying rates. If a dog sheds more
often it is more noticeable than if he sheds extensively but at irregular
intervals for a period of several weeks. Indoor dogs, because of artificial
heat and more importantly light, tend to shed in a more or less continuous
fashion. Dogs kept outside tend to shed for several weeks during major seasonal
changes, most notably in spring and fall. Usually they grow more secondary
hairs or underfur in the fall for warmth. In the spring they lose the underfur
and replace much of it with the longer primary or guard hairs. The hair coat
changes in appearance and texture but the absolute numbers of hair follicles
and hair does not.
Hair growth
The hair of a dog does not
grow continuously, but in cycles, similar to our eyebrows. Anagen is the first
phase, in which the hair is produced. It grows along side the old hair which is
subsequently lost. Catagen is an intermediate stage in the cycle, and telogen
is the resting phase in which the follicle is basically dormant. The hair
follicles are not all in the same phase at the same time, which is why we do not
see a lot of completely bald dogs!