"Collie nose" is used to describe a condition in which breeds with little or no pigment on their face develop lesions, usually on the nose, eyelids and lips. The lesions are caused by a hypersensitivity to sunlight. Despite the term "Collie nose", breeds other than Collies can also be affected, especially Shetland Sheepdogs. Collie nose has an inherited component and is worse in areas with sunny climates.
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Nasal dermatoses of dogs may be caused by many diseases. Lesions may affect the bridge of the nose, the planum nasale, or both. In pyoderma, dermatophytosis, and demodicosis, the haired portions of the nose are affected. In lupus or pemphigus, the whole muzzle is often crusted (with occasional oozing of serum) or ulcerated. In systemic and discoid lupus, and occasionally in pemphigus and cutaneous lymphoma, the planum nasale is de-pigmented, erythematous, and eventually may ulcerate. Nasal dermatosis due to solar radiation probably is a rare disease, often a misdiagnosis for the lupus variants. In true nasal solar dermatitis, the non-pigmented areas of the planum nasale are affected first, and occasionally the bridge of the nose may become inflamed and sometimes ulcerated. The lesions are worse in the summer, although lupus and pemphigus may also show this seasonal variation. Any of the above diseases may affect the periocular areas. The sudden onset of nasal swelling, erythema, and exudation is often eosinophilic furunculosis; this is thought to be caused by an insect sting or bite.
Treatment depends on etiology. Diagnostic tests should include skin scrapings, bacterial and fungal cultures, and biopsies for both histopathology and immune testing. If the diagnosis is nasal solar dermatitis, a topical corticosteroid lotion (betamethasone valerate, 0.1%) is helpful in relieving inflammation. Exposure to sunlight must be severely curtailed. Topical sunscreens may be effective but need to be applied at least twice daily. Treatment for eosinophilic furunculosis is systemic corticosteroids, prednisone or prednisolone at 1 mg/kg, b.i.d., for 1 wk, the dosage then gradually decreased.
Keeping the dog out of the sun and treating the ulcerated area with a steroid preparation will certainly help. Once the nose is healed, it can be blackened with tattoo ink to protect it from sunlight.
Usually the lesions appear as pink, raw areas about the nose and occasionally on the eyelids. The hypersensitive areas may actually ulcerate and develop a crusty scab-like covering. The condition may vary from mild irritation to severe ulcerating lesions that hemorrhage.
Left untreated, severe discomfort can result. As the nasal tissues become deeply irritated, they may crack, bleed and impair breathing. All cases should begin treatment in the early stages. Advanced stages may develop into a form of cancer which can be deadly.