In pemphigus, the autoantibody is directed against the walls of the skin cells. These cells lose their ability to remain attached and separate, forming blebs, vesicles, and pustules. The exact stimulus for the pemphigus antibody is unknown. Four types of pemphigus are seen in dogs. All are best diagnosed by skin biopsy. Serologic blood tests are helpful, but false positives and false negatives are common.
Pemphigus foliaceus is the most common autoimmune skin disease of dogs. It generally occurs in dogs 2 to 7 years of age. Predisposed breeds include Akitas, Bearded Collies, Newfoundlands, Chow Chows, Dachshunds, Doberman Pinschers, Finnish Spitz, and Schipperkes.
Pemphigus foliaceus is a pustular dermatitis that begins with red skin patches that involve the face and ears, but often becomes generalized. The patches rapidly progress to blisters and pustules, which then become dry, yellow crusts. The crusts adhere to the underlying skin and hair. Areas of depigmentation occur as the disease progresses.
Pemphigus foliaceus can involve the feet, causing thickening and cracking of the foot pads, and pain when the dog puts weight on her feet. In some cases the disease involves only the foot pads. Pemphigus foliaceus should be considered whenever a dog with a painful limp has thickened or cracked foot pads.
Pemphigus erythematosus is a localized variant of pemphigus foliaceus with involvement limited to the face, head, and foot pads. Collies and German Shepherds appear to be at greatest risk. The disease is easily confused with discoid lupus erythematosus.
Pemphigus vulgaris is an uncommon disease in which blisters and ulcers form at the junction of the skin and the mucous membranes. It involves the lips, nostrils, and eyelids. It can also attack the nailbeds, with subsequent shedding of the nails.
Pemphigus vegetans is an extremely rare form of pemphigus vulgaris. It is characterized by flat-topped pustules in the skin folds of the armpits and groin. Characteristically, the lesions heal with wartlike growths.
Treatment: There is no cure for any form of pemphigus, but more than 50 percent of dogs with pemphigus foliaceus and pemphigus erythematosus can be kept relatively free of symptoms using corticosteroids alone, or corticosteroids in combination with immunosuppressive drugs such as cyclophosphamide, azathioprine, or chlorambucil. Treatment is life long. Sunscreen applied to the depigmented skin of the nose helps to prevent ultraviolet injury.
Pemphigus vulgaris and pemphigus vegetans respond less well to treatment.