The Dog with Nasal Dermatitis

Table 2-7. Differential Diagnoses, Commonly Affected Sites, Recommended Diagnostic Tests, Treatment Options, and Prognosis in a Dog with Nasal Dermatitis

Disease

Affected Sites

Diagnostic Tests

Treatment

Prognosis

Discoid lupus erythematosus* (Immune-mediated reaction against basal cell layer may be aggravated by UV-light exposure)

Planum nasale, periocular area, lips, dorsal muzzle, pinnae (Fig. 2-42)

Biopsy

Sun avoidance, water-proof sun screens, vitamin E(200 - 400 mg q 12 hr), doxycycline and niacinamide, immuno-suppressive therapy

Fair

Pemphigus foliaceus (Immune-mediated reaction against dismonormal proteins)

Planum nasale, periocular area, lips, dorsal muzzle, inner surface of pinnae, foot pads, groin, claw folds, nipples (in cats) (Fig. 2-21, Fig. 2-22, Fig. 2-23, and Fig. 2-43)

Biopsy

Immunosuppressive therapy

Fair

Bacterial infection (typically by Staphylococcus intermedius and typically secondary to an underlying disease)

Depigmentation of planum nasale in German Shepherd Dogs with atopy (Fig. 2-44)

Cytology, biopsy

Antibacterial treatment

Good, if underlying disease can be identified and treated appropriately. Relapse likely, if this is not possible

Demodicosis (probably a hereditary specific T-cell defect that permits abnormal proliferation of Demodex canis, a normal commensal mite of canine skin. This proliferation leads to a further parasite-induced immunosuppression. Adult-onset demodicosis frequently secondary to hormonal diseases, neoplasia, steroids, or other chemotherapy.)

Localized form: Focal erythema, alopecia and scaling, most commonly on the face (< 4 sites). Generalized form: Erythema, alopecia, papules, plaques, pustules and crusts where large areas, more than 5 areas, or paws are involved (Fig. 2-15, Fig. 2-16, and Fig. 2-17)

Deep skin scrapings, hair plucks, biopsy, elimination diet

Localized form: 95% resolve spontaneously, thus benign neglect or antimicrobial treatment only. Generalized form: Amitraz, ivermectin, milbemycin, antibacterial treatment for secondary infection

Fair

Dermatophytosis (dermatophytes are transmitted by contact with fungal elements)

Face, pinnae, paws (Fig. 2-18)

Wood's lamp, trichogram, fungal culture, biopsy

Antimycotic agents such as griseofulvinor ketoconazole. Topical antifungal shampoos may decrease contamination of environment.

Good

Sporotrichosis* (caused by ubiquitous dimorphic fungal saprophyte Sporothrix schenkii that infect wounds) Zoonosis, although zoonotic potential of canine sporotrichosis is much lower than that of feline sporotrichosis

Multiple nodules or ulcerated plaques on the head, pinnae, and trunk.

Biopsy, fungal culture

Antimycotic therapy with iodides or azoles

Fair

Cryptococcosis* (Rare infection in often immunocompromised host with ubiquitous, saprophytic, yeast-like fungus Cryptococcus neoformans)

Upper respiratory, cutaneous, central nervous and ocular signs. Papules, nodules, ulcers and draining tracts. Nose, lips, and claw beds maybe affected.

Cytology, biopsy, fungal culture, serologic testing

Antimycotic therapy with amphotericin Bpossibly in combination with ketoconazole or itraconazole

Fair