Pododermatitis is not a specific diagnosis but more the description of a clinical presentation, namely inflammation of the feet. Specific terms are used to describe lesions involving the feet and nails. The most commonly used terms include onychomadesis (sloughing of claws), onychogryphosis (hypertrophy and abnormal curvature of claws), paronychia (inflammation of the nail fold) and onychodystrophy (abnormal claw formation).
Numerous diseases can involve pododermatitis and consequently the footpads and nails. Diseases that can cause pododermatitis, usually without involvement of the footpads and nails, include atopy, food allergy, contact allergy, demodicosis, hookworm and Pelodera infestation, sarcoptic mange, dermatophytosis, Malassezia and bacterial infections.
Diseases that commonly affect the footpad causing crusting and ulcerations include: vasculitis; systemic lupus erythematosus; necrolytic migratory erythema (also called hepato-cutaneous syndrome); pemphigus complex (foliaceous and erythematosus); drug eruptions (e.g. erythema multiforme); zinc responsive dermatosis; generic dog food dermatosis, mycosis fungoides (also called cutaneous lymphoma); and primary diseases of keratinization.
Diseases that may cause brittle and deformed nails include: dermatophytosis, symmetric lupoid onychodystrophy, and idiopathic symmetric onychodystrophy of Siberian huskies and Rhodesian ridgebacks.
Related Symptoms or Ailments
Symmetric lupoid onychodystrophy. It has been reported in Labradors, German shepherds, Rottweilers and boxers. Affected dogs are usually young and nail loss begins acutely and is associated with variable degree of pain and itchiness. Paronychia is generally absent.
Secondary bacterial infections are common and contribute to the pain and itchiness. The natural course of the disease involves partial nail re-growth of friable, abnormal nails that continue to be sloughed. Diagnosis is obtained with P3 amputation and histopathology.
Fungal infections of the nails are most commonly caused by mycrosporum gypseum or trychophyton. The affected claw is misshapen and friable. Paronychia is common. Diagnosis is made by culture of shavings or clipping taken from the nail.
Pelodera pododermatitis is caused by free living nematodes. The larvae invade the skin and may be found on skin scrapings. Infestation is self-limiting once the source of contamination has been removed. Destruction of bedding is mandatory and the patient should be washed with parasiticidal dip.
Hookworm infestation (Ancylostoma and Uncinaria) is a disease of kenneled dogs in poor sanitary conditions. Larvae penetrate the skin and cause an itchy, papular pododermatitis. The footpads become spongy and soft, especially at the margins. The chronic inflammation causes the nails to grow rapidly they may be deformed and break off easily. Diagnosis is based on a history of poor sanitation, clinical signs and positive fecal. Larvae are difficult to find on biopsies.
Idiopathic digital hyperkeratosis is a disorder of older dogs, sometimes seen in conjunction with hyperkeratosis of the planum nasale. Cocker spaniels are predisposed. Hyperkeratotic "feathers" are found at the margins of the pads. In some cases tissue may be so hard that fissures are the result. Diagnosis is based on clinical signs and biopsy.
Bacterial infections of the nails is usually secondary to trauma. Infections are associated with a significant paronychia, toe swelling and pain. Osteomyelitis may develop in some cases. Staphylococcus is usually isolated from these lesions.