by Judy Seltzer, BVetMed, MRCVS, DACVD
Pemphigus foliaceus is an autoimmune disease where antibodies produced by an animal’s own immune system attack the bridges that hold skin cells together. The deposition of antibody in intercellular spaces causes the cells to detach from each other within the uppermost epidermal layers- this is known as acanthosis. Pemphigus foliaceous is the most common autoimmune disease diagnosed in dogs and cats.
Dogs and cats of any age or gender can be affected. In dogs, Akitas, Chow Chows, Doberman Pinschers, Dachshunds, and Newfoundlands may be predisposed. No breed predilections exist with cats. Three forms of pemphigus foliaceus exist in the dog. The first and most common is the idiopathic form which develops in dogs with no history of skin disease or drug history. The second form of pemphigus foliaceus is initiated via a drug reaction. Some drugs such as cephalosporins, sulfonamides and penicillin have previously been linked to the development of pemphigus. The third form occurs in dogs with a history of chronic skin disease (e.g. allergies).
The primary lesion of pemphigus foliaceus is a pustule (a small pus filled lesion). These lesions typically begin along the nasal bridge, around the eyes, and the pinnae of the ears. It is typical for the lesions to spread and occur along the trunk, feet, clawbeds, groin, and footpads. In cats, the nail beds and nipples can also be commonly affected. In most cases, the pustules form and rupture very quickly and are rarely seen. Instead, we often observe areas of hair loss, yellow-brown dried crusts, redness and scale. These skin lesions are variably pruritic. Severely affected animals may become anorexic, depressed and have a fever. The disease itself often displays a waxing/waning course.
The diagnosis of pemphigus foliaceus is made by a combination of clinical signs, cytology, and biopsy. Cytology of a pustule will often show neutrophils, acantholytic cells and occasionally eosinophils. Other diseases that can appear similar to pemphigus foliaceus include infection (bacterial, parasitic, fungal), seborrheic skin disease, and varying forms of lupus. Skin scrapes are often performed to rule out external parasites via microscopic analysis. A fungal culture should be performed to rule out ringworm. In most cases, multiple skin biopsies are required to confirm the diagnosis of pemphigus foliaceus. Dermatohistopathology will normally reveal subcorneal pustules containing neutrophils and acantholytic cells, with variable numbers of eosinophils. Bacterial cultures may be negative but bacteria may be isolated if secondary infections are present.
Focal cases of pemphigus foliaceus can be treated with varying strengths of topical steroids. The mainstay of therapy for more generalized cases in both dogs and cats are oral glucocorticoids (e.g. prednisone) in combination with steroid-sparing immunosuppressive medications. These non-steroidal immunosuppressive drugs are used In order to minimize the potential side effects of glucocorticoids (e.g. weight gain, excessive drinking and urinating, liver enlargement). In dogs, azathioprine and/or cyclosporine can be utilized, while in cats, chlorambucil and/or cyclosporine are the most popular supportive drugs. Other non-steroidal immunosuppressive drugs include gold salts (dogs and cats) and tetracycline/niacinamide (dogs). Affected animals are started at higher dosages initially until remission is achieved (approximately 4-12 weeks), and are then tapered to the lowest possible dosages that maintain remission.
The prognosis is fair to good, but lifelong therapy is usually required to maintain remission. Cases of pemphigus foliaceus that are induced by a drug reaction, are the most likely to be cured. Regular monitoring of clinical signs, complete blood counts serum biochemistry profiles, urinalyses, and urine cultures with treatment adjustments as needed are essential.
Judy Seltzer, BVetMed, MRCVS, DACVD
Veterinary Medical Center of Long Island
75 Sunrise Highway
West Islip, New York 11795
(631) 587-0800; fax (631) 587-2006