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     Canine pododermatitis       

 (Interdigital pyoderma, Pedal Folliculitis. furunculosis)

                

talalogoa


This condition is a common inflamatory skin disease of dogs which can be frustrating to the owner. Pododermatitis is a group of several different skin disorders which affect the skin webs between the toes and between the foot pads that can be caused by many disorders including infectious, allergic, or hormonal disorders, immune-mediated diseases, tumors or cancers and environmental contaminants. The result is inflammation (reddness) or swellings, sometimes with discharging sinuses. The underlying cause is often unknown.  Secondary bacterial  infection can be present.  Symptoms include excessive licking and biting of the feet and lameness.  There will be redness and sometimes swelling with or without ulcers or sinus  formation.  If left untreated, pododermatitis can develop into a chronic condition which is exascerbated by the dog constantly nibbling away at itself causing self-trauma.  Secondary infection can become established in the open wounds.  Diagnosis is based on medical history and clinical signs. Additional tests such as bacterial culture and antibiotic sensitivity tests, fungal cultures, biopsies of the lesions, blood and urine tests will help to eliminate any underlying hormonal disorders such as hypothyroidism, hypoallergenic food trials and radiographs will be performed based on your pet’s specific needs. Skin scrapings for parasites, laboratory culture and sensitivity testing for micro-organisms may be needed. 

Treatment
Treatment of the underlying cause (if one can be identified) is essential . Once a specific diagnosis is made, treatment will be directed toward that cause.  If the pododermatitis has an allergic or immune-mediated cause, it is important to note that the condition will not be cured.  In these cases, the therapeutic goal is to minimize clinical signs and recurrences. Antibiotic therapy is needed if bacterial infection (primary or secondary) is present.

Regular bathing in salty water, or in an antiseptic solution (such as chlorhexidine) for 15 minutes 2-3 times daily is often recommended. Excess hair should be carefully clipped from between the toes and pads to prevent foreign material being collected and causing irritation.

Changing surfaces that the animal is exercised on may help identify a contact problem. For example, dogs usually exercised on pavements can be exercised exclusively for a period on grass, or vice versa. Dogs kept indoors on nylon carpets can be kept in rooms with wool carpets.

For localised lesions surgical exploration may be needed to find foreign penetrating material (eg grass seeds) and sometimes surgical removal (excision) of isolated lesions is performed.

In some cases treatment is unsuccesfull and will return later in life.  The open lesions that heal will leave scars on the feet.
Known Causes of Pododermatitis
Most cases are idiopathic - i.e. the cause is unknown

Foreign object penetrations into the skin - grass awns, splinters of wood, thorns

Foreign material collected against the skin - tar, gravel, sand, chemicals, wlaking on freshly laid ("green") concrete

Trauma - eg grazes, cuts, bruises

Cancer

Clipper rash

Infections - bacteria, Staphylococcus, Pseudomonas, Proteus, Mycobacterium, Nocardia and Actinomyces
fungul - Dermatophytes (ringworm), sporotrichosis, mycetoma, blastomycosis, and cryptococcosis
parasites - mange mite(eg demodex mite) , soil nematode and hookworms

Psychological disorders - German Shepherd Dogs, Poodles and some Terriers.

Sterile pyogranulomas - English Bulldogs, Dachshunds, Great Danes, Boxers - cause unknown.

Immune disorders - including autoimmune disease (pemphigus vulgaris, bullous pemphigoid, pemphigus foliaceus, systemic lupus erythematosus, erythema multiforme, toxic epidermal necrolysis, vasculitis, cold agglutinin disease,

Direct contact allergy -  Atopy or seasonal allergies, food hypersensitivity, allergic contact dermatitis

Hormonal or Metabolic - Hypothyroidism, hyperadrenocorticism (Cushing’s disease), hepatocutaneous syndrome (necrolytic migratory erythema – rare)

Tumors - Squamous cell carcinoma, melanoma, mast cell tumor, keratoacanthoma, inverted papilloma, eccrine adenocarcinoma

Drug reactions

Zinc-deficiency

Canine distemper virus

Clinical Signs of Pododermatitis

Infectious – The feet and paws are often red and swollen. There may be nodules or fungal lesions (kerions), ulcers or discharge from the lesions. There is often hair loss and the dog may lick the feet constantly.  

Allergic – The feet are red and inflamed, and swelling is usually present. Itching is a constant problem with the tops of the paws most commonly involved. There is usually reddish brown staining of the fur from pigments naturally present in the saliva. In cases of contact pododermatitis (walking or contacting an offensive substance), the undersides of the paws are usually involved, although the entire paw may be affected. 

Immune-mediated – The most common clinical signs are crusts (scabs) and ulcerations with occasional blisters. All four feet are commonly involved, especially the footpads and nailbeds. Excessive darkening of the tissues and thickened, crusty footpads with erosive lesions may be present, especially in cases of pemphigus foliaceus. 

Hormonal or metabolic – Lesions are usually related to secondary skin infections and include pustules, redness and inflammation.  

Tumors – Usually only one foot is involved and there may be a nodule, or one or more ulcers. Multiple feet may be involved in squamous cell carcinoma of the nailbed.  

Environmental – One or more feet may be involved, depending on the cause or contact status. Most dogs experience chronic interdigital inflammation, ulceration, abscesses and discharge with or without itching.

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