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

224 •DOG OWNER’S HOME VETERINARY HANDBOOK
NASAL SOLAR DERMATITIS (COLLIE NOSE)
This is a weepy, crusty dermatitis that affects Collies, Australian Shepherds,
Shetland Sheepdogs, and related breeds. It is seen most commonly in sunny
regions such as Florida, California, and the mountainous regions of the West.
It is caused by lack of pigment on the nose and prolonged exposure to the
ultraviolet rays in sunlight. Lack of pigment is hereditary in some dogs, but it
can be acquired through skin diseases and scarring.
Initially, the skin appears normal except for the lack of black pigment.
With exposure to sunlight, the skin at the border between the muzzle and
nose becomes irritated. As the irritation continues, hair falls out and the skin
begins to ooze and crust. With continued exposure, the skin breaks down. In
advanced cases, the whole surface of the nose becomes ulcerated and the tip
itself may disappear, leaving unsightly tissue that bleeds easily. Skin cancer
may develop.
Nasal solar dermatitis must be distinguished from discoid lupus erythematosus,
pemphigus foliaceus, and zinc responsive dermatosis—skin diseases discussed
in chapter 4. All three diseases produce a skin reaction similar to nasal
solar dermatitis. A distinguishing feature of nasal solar dermatitis is that pigment
was lacking before the disease developed. In the other three, the pigment
disappears as the disease progresses. Note that once depigmentation occurs in
dogs with these diseases, the damaging effects of sunlight add to the problem.
Treatment: Prevent further exposure by keeping your dog indoors as much
as possible when the sunlight is the most intense—between 9 a.m. and 3 p.m.
Letting the dog out on cloudy days does not address the problem, because
ultraviolet rays penetrate clouds. Sunscreens are of some aid in protecting
These crusts and ulcerations
of the skin on the
nose were caused by
nasal solar dermatitis.