Page 1342 - Cote clinical veterinary advisor dogs and cats 4th

Nasal Cutaneous Disorders 677

RISK FACTORS
• Sun exposure can cause or aggravate canine
VetBooks.ir pemphigus erythematosus. Diseases and Disorders
and feline solar dermatitis, DLE, SLE, and
○ Lack of skin pigmentation can predispose
to sun damage.
• Susceptible dogs fed diets high in phytates
(high-cereal content) or in minerals such
as calcium can develop zinc-responsive
dermatosis.
CONTAGION AND ZOONOSIS
Contagion (e.g., dermatophytosis) and/or
zoonosis (e.g., feline sporotrichosis) possible,
depending on the cause
GEOGRAPHY AND SEASONALITY
• Animals living in sunny climates more com-
monly develop photoaggravated dermatitis.
• Animals living in areas endemic for leish- NASAL CUTANEOUS DISORDERS Proliferative nasal arteritis in an 8-year-old, male Saint Bernard. Note
the ulcerative lesion on the nasal philtrum. (Courtesy Dr. Nadia Pagé.)
maniasis are susceptible to the disease.
ASSOCIATED DISORDERS
• Granulomatous uveitis in uveodermatologic folliculitis, furunculosis, granulomatous • Hereditary (see Genetics, Breed Predisposi-
syndrome lesions). tion above)
• Systemic disease in SLE • Altered cornification process results in • Pigmentary: nasal depigmentation (Dudley
• Hepatopathy or glucagon-producing pancre- hyperkeratosis. nose), seasonal nasal hypopigmentation (snow
atic tumor in superficial necrolytic dermatitis • Development of antibodies or activated lym- nose), vitiligo, alopecia and melanoderma,
phocytes against normal body constituents lentigo simplex
Clinical Presentation (autoimmune diseases) or against inciting • Metabolic/endocrine: superficial necrolytic
HISTORY, CHIEF COMPLAINT antigens (drugs, bacteria, viruses) leads to dermatitis (hepatocutaneous syndrome),
Presentation depends on the underlying disease: tissue damage. canine hypothyroidism
• Nonpruritic hair loss confined to the bridge • Defective melanin production or destruction • Nutritional: zinc-responsive dermatosis
of the nose (e.g., localized demodicosis, local- of melanocytes leads to pigment disorders; a • Environmental/traumatic: phototoxicity
ized dermatophytosis) or with a generalized disturbance at the dermoepidermal junction (sunburn), contact dermatitis, local trauma
dermatopathy (e.g., generalized demodicosis, can cause hypopigmentation. • Drug eruption: from topical or systemic
dermatophytosis, endocrinopathies) • Solar exposure of poorly pigmented nasal skin administration
• Pruritus and facial rubbing, with secondary results in a phototoxic reaction (sunburn) • Neoplastic: squamous cell carcinoma
nasal alopecia in cases of allergic disease or and immune-mediated diseases, such as (SCC), basal cell carcinoma, epitheliotro-
intranasal foreign bodies (usually accompa- pemphigus erythematosus, SLE, and DLE; pic lymphoma, fibroma, feline sarcoid,
nied by sneezing and/or nasal discharge) can also be photoaggravated. others
• Erosions and ulcers in cases of immune- • Miscellaneous: sterile granuloma/pyo-
mediated diseases or nodules and plaques DIAGNOSIS granuloma syndrome, reactive cutaneous
(e.g., neoplastic, cutaneous histiocytosis, and systemic histiocytosis, nasodigital
fungal diseases) Diagnostic Overview hyperkeratosis
• Signs of systemic illness may be reported The presenting complaint of nasal cutaneous
concurrently with generalized disorders abnormalities warrants a dermatologic exam. Initial Database
(e.g., systemic mycoses, SLE, systemic Selection of diagnostic tests is based on history • Wood’s lamp (cats > dogs): dermatophytosis
histiocytosis). and physical exam. (fluorescent strains of Microsporum canis
[p. 247])
PHYSICAL EXAM FINDINGS Differential Diagnosis • Skin cytologic exam (p. 1091): phagocytized
Any of the following are possible, depending • Infectious bacteria, inflammatory cells, acantholytic
on the cause and severity: ○ Bacterial: mucocutaneous pyoderma, nasal keratinocytes (pemphigus), fungal organisms
• Nasal depigmentation or hyperpigmentation pyoderma, feline leprosy • Skin scrapings (p. 1091): Demodex spp
• Alopecia ○ Fungal: dermatophytosis, sporotrichosis, • CBC, serum biochemistry profile, urinalysis
• Erythema cryptococcosis, aspergillosis, blastomycosis, (if concurrent systemic disease is suspected):
• Papules/pustules/vesicles histoplasmosis results depend on underlying cause and are
• Erosions/ulcers ○ Parasitic: demodicosis often normal or show nonspecific changes
• Crusts ○ Protozoal: leishmaniasis when cause is not systemic.
• Hyperkeratosis ○ Rickettsial: canine Rocky Mountain • Ocular exam (if vision loss or visible ocular
• Nodules/plaques spotted fever, canine ehrlichiosis lesions): uveitis (uveodermatologic syndrome)
○ Viral: canine distemper; herpesvirus and (p. 1137)
Etiology and Pathophysiology calicivirus infections in cats • Thoracic and abdominal imaging, if relevant,
Nasal lesions arise from various pathologic • Immune-mediated: pemphigus foliaceus and to confirm systemic disease or stage tumors
mechanisms: erythematosus, SLE, DLE, uveodermatologic
• Infectious agents induce an immune syndrome, canine proliferative arteritis of the Advanced or Confirmatory Testing
response from the host, resulting in nasal philtrum, canine eosinophilic furuncu- • Skin biopsies for histopathologic evalu-
tissue inflammatory cell infiltrates (e.g., losis, feline mosquito bite hypersensitivity ation: indicated when initial database is

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