Cutaneous disorders of the paw remain a challenging clinical entity and pododermatitis, although involving many possible causes, invariably appears uniformly similar clinically.
There are a number of recognized underlying causes of canine pododermatitis, including:
- Atopy and dietary allergies
- Trauma, foreign bodies (such as grass seed penetrations of the digit), chemical burns
- Acral lick dermatitis
- Superficial necrolytic dermatitis
- Calcinosis cutis
- Lymphocytic-plasmacytic pododermatitis - immunomodulatory-responsive
- Erythema multiforme
- Interdigital bacterial pyoderma
- Pemphigus foliaceus
- Systemic lupus erythematosus
- Zinc-responsive dermatosis
- Vitamin A–responsive dermatosis
- Toxic epidermal necrolysis and drug eruptions
- Malassezia spp dermatitis
- Skin parasites - Demodex spp, Leishmania spp, Schistosoma spp, Ancylostoma spp
Various hypotheses have been proposed to explain the pathogenesis of idiopathic pododermatitis including pedal conformation, food allergy, trauma, immunosuppression, bacterial infection, furunculosis and dermal granuloma formation. However, many dogs display localized upregulated T- and B-lymphocyte responses within the skin lesions, and this may contribute to the pathogenesis of the skin lesions observed in many affected dogs.
Clinically affected dogs often present with symptoms such as lameness, pedal pruritus, erythema, swelling, pain and alopecia of the feet. The lesions produced in the pedal region are very varied in nature and can affect the digits, nails, interdigital space or pads. Close examination may reveal varying degrees of tumefaction, erythema, papules, saliva stain due to licking, hyperpigmentation, alopecia, nodules with serohaemorrhagic or purulent content, desquamation, crusts or fistulae.
As pedal lesions are reported in many canine dermatoses, a methodical series of diagnostic tests is required to establish the underlying aetiology. However, laboratory/ancillary investigations may prove unrewarding, prompting a diagnosis of idiopathic disease.
Diagnosis is usually confirmed on histopathologically, characterized by varying degrees of epidermal hyperplasia, hyperkeratosis, spongiosis, dermal oedema and perivascular aggregates of lymphocytes and plasma cells.
Although non-responsive to antimicrobial therapy, antiparasitic agents and elimination diets, these dogs typically respond well to immunomodulatory therapy such as prednisolone, cyclosporin, tacrolimus or azathioprine.
- Purina Care
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