Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

C h a p t e r
THE NOSE
A dog’s nose is made up of the nostrils (also called nares) and the nasal cavity,
which runs the length of the muzzle. The nasal cavity is divided by a midline
partition into two passages, one for each nostril (see the figure Anatomy of the
Head, page 232). These passages open into the throat behind the soft palate.
The dog has two major sinuses that connect with the nasal cavity: the maxillary
and the frontal.
The nasal cavity is lined by a mucous membrane called the mucociliary
blanket, which is abundantly supplied with blood vessels. This blanket acts as
a defense against infection by trapping bacteria and foreign irritants and conveying
them to the back of the throat through the actions of tiny hairlike
structures called cilia. At the back of the throat, foreign particles are trapped
in mucus and either coughed out or swallowed. Dehydration or exposure to
cold air stops the motion of the cilia and thickens the layer of mucus. This
reduces the effectiveness of the mucociliary blanket.
The nasal cavity is extremely sensitive and bleeds easily when traumatized.
An otoscope and nasal forceps are used to remove foreign bodies. Instruments
passed into the nasal passages cause violent sneezing, however, so heavy sedation
or anesthesia is required to conduct a thorough examination.
Most dogs have darkly pigmented noses, but brown, pink, and spotted
noses are normal for some breeds. In some dogs with pink noses, the nose will
darken in summer and then lighten up again in winter. This is normal (see
Snow Nose, page 225).
The moisture at the tip of the nose is secreted by mucous glands in the
nasal cavity. A dog’s nose is normally cool and moist, but may be warm and
dry, depending on the dog’s activity and state of hydration, and the temperature
and humidity. A warm, dry nose does not necessarily indicate that a dog
has a fever. If you suspect fever, confirm it with a rectal thermometer.
There is a rich supply of nerves in the nasal cavity of dogs—far greater than
in most other animals. These nerves ultimately connect with the highly
developed olfactory center in the dog’s brain. The abundant nerve supply and
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