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

212 •DOG OWNER’S HOME VETERINARY HANDBOOK
MARGINAL SEBORRHEA
This is a skin disease caused by a buildup of skin oil (sebum) on the hair along
the edges of the ear flaps. The hair has a greasy feel. When rubbed with a
thumbnail, the hair falls out. The disease is most common in Dachshunds.
Treatment: Marginal seborrhea is incurable, but it can be controlled by
bathing the ears with benzoyl peroxide or a sulfur-tar shampoo (see Seborrhea,
page 150). Soak the ear margins in warm water (using compresses) before
shampooing. Put cotton balls in the ear canal to prevent any water from dripping
down into the ear. Repeat every 24 to 48 hours until all the greasy material
has been removed. Use a moisturizer to keep the ears soft and pliant.
Repeat the treatment as necessary. If the skin is severely inflamed, apply
1-percent hydrocortisone ointment.
The Ear Canal
EXTERNAL OTITIS
External otitis is an infection of the ear canal. The ear canals are delicate
structures and are easily infected. Eighty percent of infections occur in breeds
with long, dropped ears. This is a function of lack of air circulation; open,
erect ears dry out more easily than dropped ears and therefore provide less
favorable conditions for bacterial growth.
Many factors contribute to the development of external otitis. Some
breeds (such as the Chinese Shar-Pei) are predisposed because of narrow or
stenotic ear canals. Other breeds may be predisposed because they have an
abundance of hair that blocks the circulation of air. Many dogs with allergic
skin diseases, particularly canine atopy and food hypersensitivity dermatitis,
are predisposed to ear infections as part of the generalized skin response.
Similarly, dogs with primary and secondary seborrhea often have ear canal
involvement characterized by a buildup of yellowish oily wax that provides an
excellent medium for bacterial growth. Foreign bodies such as grass seeds and
foxtails, and growths in the ear canal, are other predisposing causes. Ear mites
(see page 214) can precede bacterial otitis.
Iatrogenic causes of infection include using cotton-tipped applicators to
clean the deep recesses of the ears, allowing water to get into the ears during
bathing, excessive and improper cleaning of the ears, and a grooming routine
that calls for plucking or clipping hair in the external ear canals.
Signs of external otitis are head-shaking and scratching and rubbing at the
affected ear. The ear is painful. The dog often tilts or carries her head down on
the painful side and cries or whines when the ear is touched. An examination
reveals redness and swelling of the skin folds. There usually is a waxy or purulent
discharge with a bad odor. Hearing can be affected.