Summary
Pemphigus is a relatively uncommon autoimmune disease that can affect the skin of dogs. In all four of the disease's forms (pemphigus foliaceus, pemphigus erythematosus, pemphigus vegetans and pemphigus vulgaris) antibodies attack skin components, leading to a painful separation of the skin. Blisters, ulcers, erosions, pustules and crusting are common manifestations of this small group of diseases.
While a hereditary predisposition is assumed given the breed predilections observed for p. foliaceus and p.eythematosus, neither p. vulgaris nor p.vegetans have been associated with any particular breed. Consequently, only the first two forms of pemphigus will be described in the remainder of this article.
The mode of inheritance for pemphigus is unknown.
Pemphigus foliaceus is the most common of the two breed-associated pemphigus diseases. It is often thought of as a more severe form of p. erythematosus.
Symptoms and Identification
Both p. foliaceus and p. erythematosus appear in dogs in mid-life at around four years of age. Lesions first appear on the face and ears and will look like crusty, pustular wounds. In the case of p. foliaceus, the lesions will usually spread to the groin and feet. Itchiness and pain may be associated with them, as well. Some dogs may feel lethargic and inappetant.
The nasal area (bridge and muzzle) of many dogs is a prominent location for many of these lesions. Due to the erosive nature of the disease, pemphigus patients can become very photosensitive in these locations leading to severe sunburns in many cases
Diagnosis is achieved via skin biopsy and by ruling out other similar-looking skin diseases through skin scrapings, blood testing, etc.
Affected Breeds
For pemphigus foliaceus, the Bearded Collie, Akita, Doberman Pinscher, Newfoundland and Schipperke are known to be predisposed. In the case of pemphigus erythematosus, German Shepherd (and its mixes) and the Collie are predisposed.
Treatment
As with so many autoimmune diseases and skin disorders in general, pemphigus is considered a difficult and frustrating disease to treat. Suppressing the aberrant response of the dog's immune system is imperative, but this is typically impossible to achieve without recruiting a list of side effects along the way.
Corticosteroids like predinisone and/or other immune system-suppressing drugs are typically used. Long-term therapy is required. Tetracycline and niacinamide has been described as an effective approach for some p. erythematosus cases. Milder cases of p. erythematosus may respond to topical steroids and sun avoidance alone.
Veterinary Cost
The cost of diagnosing the condition can be steep if one considers the need to recruit the assistance of a veterinary dermatologist in many pemphigus cases, particularly for those that are recalcitrant to medical therapy. $300 to $1,000 if a fairly typical up-front diagnostic expense.
Treatment with corticosteroids is considered inexpensive, but when other immunomodulating drugs are required, the drugs can be prohibitively priced. It's also the case that dogs who respond poorly to immunosuppressive drugs may suffer side effects that can require expensive treatment in their own right.
Prevention
Though inheritance modalities have not yet been established, it's considered advisable to refrain from breeding affected dogs and their first degree relatives (parents and siblings).
References
Scott, D.W., Miller, W.H., Griffin, C.E. 1995. Immunologic Skin Diseases. In Muller and Kirk's Small Animal Dermatology. p. 500-518. W.B. Saunders Co., Toronto.