What is pododermatitis?
Pododermatitis is a term used to describe inflammation of the feet or paws.
What causes pododermatitis?
Pododermatitis has many different causes. Some of the specific causes of pododermatitis include:
- Infectious causes include bacteria, yeast, fungal and parasites
- Allergic disease including atopy, seasonal allergies, food hypersensitivity and allergic contact dermatitis
- Immune-mediated disease such as pemphigus foliaceus and systemic lupus erythematosus
- Hormonal or metabolic disease including hypothyroidism, hyperadrenocorticism (Cushing’s disease) and hepatocutaneous syndrome
- Tumors including squamous cell carcinoma, melanoma and mast cell tumor
- Irritant contact dermatitis ie from trauma, excessive exercise or running on hard surfaces, clipper burn, or foreign bodies of the skin like a splinter
Questions that may be asked in order to determine the cause or causes include the following:
- What is the general environment in which the dog walks and lives?
- Do the clinical signs occur seasonally or do they persist year-round?
- Are there additional lesions elsewhere on the body?
- How effective have treatments been??
- What is the dog's diet?
- Has the dog traveled anywhere outside its usual environment?
- Does the dog have any other medical problems?
What are the clinical signs of pododermatitis?
Although signs are similar, certain clinical signs of pododermatitis can suggest a specific cause:
Infectious. The feet and paws are often red (inflamed) and swollen. There may be nodules (bumps) or fungal lesions (kerions), ulcers, or discharge (pus) from the lesions. There is often hair loss and the dog may lick the feet constantly.
Allergic. The feet are inflamed and swelling may be 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 either salivary pigments or yeast overgrowth. In cases of contact pododermatitis (walking on 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 (ulcerated) lesions may be present, especially in cases of pemphigus foliaceus.
Hormonal or metabolic. Lesions are usually caused by 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.
How is the specific cause of pododermatitis diagnosed?
Diagnosis is based on medical history, clinical signs and diagnostic testing including skin cytology, skin scrapings, and hair pluckings. Cytology is used to look for the presence or absence of inflammatory cells, as well as bacteria, yeast, and parasites. Skin scrapings and hair pluckings evaluate for parasites including demodex mites. Additional tests may include bacterial and fungal cultures, biopsies, blood and urine tests, hypoallergenic food trials, and radiographs.
How is pododermatitis treated?
Because there are a number of potential causes for pododermatitis, a specific diagnosis is needed in order to develop a treatment plan.
Once the underlying cause is determined, 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.
Treatments may include topical therapy such as shampoo washes, foot soaks, or wipes for secondary bacterial and yeast infections. Oral antibiotics and anti-fungals may be required for more severe cases. In addition, corticosteroids ( prednisone, dexamethasone), immune modulating drugs such as cyclosporine(Atopica®) and oclactinib (Apoquel ®) or immunotherapeutic injections of lokivetmab (Cytopoint®) may be required in cases involving seasonal or food allergies.
What is the prognosis for pododermatitis?
The prognosis is dependent on the underlying cause. Most dogs respond well to therapy. With simple lifestyle adjustments, they go on to enjoy relatively normal lives.