CHAPTER 40 PODODERMATITIS AND CLAW DISORDERS 591
Onychomycosis
Dogs:Trichophyton mentagrophytes– usually generalized (Figure 40.21).
Cats:Microsporum canis.
Onychorrhexis
Idiopathic: especially in dachshunds; multiple nails.
Trauma.
Infection: dermatophytosis.
Parasites:Leishmania.
Onychomadesis
Trauma.
Infection.
Immune mediated: pemphigus, bullous pemphigoid, lupus erythematosus, drug
eruption, symmetric lupoid onychodystrophy.
Vascular insufficiency: vasculitis, cold agglutinin disease.
Neoplasia: subungual squamous cell carcinoma, melanoma, eccrine carcinoma,
osteosarcoma, subungual keratoacanthoma, inverted squamous papilloma (Figure
40.22).Idiopathic.
Claw Dystrophy
Acromegaly.
Feline hyperthyroidism.
Zinc-responsive dermatosis.
Congenital malformations.
DIFFERENTIAL DIAGNOSIS
Classification based on clinical presentation.
Interdigital erythema with pruritus:
Atopic dermatitis
Food hypersensitivity
Demodicosis
Bacterial overgrowth.
Nonpruritic alopecia of the foot:
Demodicosis
Bacterial overgrowth
Dermatophytosis (Figure 40.23)
Ischemic folliculopathy (dermatomyositis, postvaccination).