Pigmentation Problems of the Nose in Dogs
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. 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
dogs who spend time outdoors. Use products containing an SPF greater than 15.
Apply the sunscreen 30 to 60 minutes before exposure and again later in the
Treat an irritated nose with a skin preparation such as Cortaid that
contains 0.5 to 1.0 percent hydrocortisone.