Pemphigus Complex – a Dermatologic Disease
Nancy McDonald, BSN, RN, retired
What is Pemphigus Complex Disease?
Pemphigus Complex is a group of autoimmune diseases affecting different layers of skin. The body’s own immune system begins attacking itself and the result is an abnormal immune response to normal components of the skin holding the cells together (desmosomes are responsible for cell-to-cell adhesion), resulting in the separation of cells (acantholysis Keratinocytes).
It is seen in dogs, cats, horses and humans, and can be a fatal disease because of secondary infections and/or damage to the mucosal linings of the mouth and esophagus and/or the serious side effects of treatment. Breed predispositions are recognized for pemphigus foliaceus (Bearded Collie, Akita, Doberman Pinscher, Newfoundland, Schipperke) and pemphigus erythematosus (Collie, German Shepherd and German Shepherd crosses). There are no predispositions recognized for the other two forms, pemphigus vulgaris and pemphigus vegetans. It is almost unheard of in the Bichon but a case has been reported.
The skin or epidermis is made up of four layers. The bottom layer or base layer is called stratum basale or basal layer where production of the structural protein keratin begins. The keratinocytes move upward into the next layer called spinosum or prickle cell layer. The cells in the third layer, having more keratin, are still alive and dividing and are called the stratum granulosum or granular layer. At the top is stratum corneum or horny layer, the layer that is visible. This layer is a thick, tough, protective layer. In dogs an even tougher, specialized layer makes up the skin of the footpads and nose leather, stratum lucidum.
Since pemphigus is an autoimmune disease, an underlying genetic component is suspected. In humans, some individuals are predisposed to developing some form of pemphigus in the presence of the right triggers. Causative agents may apply to dogs too but research lacks in this area. Due to the genetic component, dogs with a form of pemphigus complex should not be bred.
The most severe form of the pemphigus complex is pemphigus vulgaris. It affects the deep layer of the epidermis, the basal layer, and is clinically distinct from the superficial pemphigus. Pemphigus vulgaris causes severe ulcerations of the mouth, nose, prepuce, anus and vaginal area, where “normal” skin meets “specialized” skin. The mouth is almost always affected. This is extremely painful and there is a higher risk of secondary complications. There may be severe itching as well fever and loss of appetite. The Pemphigus vegetans is a less severe form of pemphigus vulgaris but it looks very different. There are warty growths over the body that may ulcerate.
The most common of the pemphigus complex is pemphigus foliaceus. It usually affects the top layer of the dog’s skin on the nose bridge, eyes, groin, ears and footpads. The results include pustules that rupture easily leaving scale, crusts, red skin, erosions, and hair loss. Secondary infections may develop as well as severe itching. Footpads may become sore and painful making it difficult to walk. Fever, loss of appetite and depression may result. The second most common of the pemphigus complex is pemphigus erythematosus and is believed to be a milder form of pemphigus foliaceus. It affects the skin on the face and ears. Both p-foliaceus and p-erythematosus affect the superficial layer of the dermis.
Pemphigus foliaceus is sometimes used as the general term for all the superficial pemphigus diseases as there is an overlap in clinical, histologic, and immunologic characteristics among all the superficial pemphigus conditions. Deep pemphigus conditions, though, still remain clinically and immunologically distinct from the superficial pemphigus conditions. Thus, the term pemphigus should not be used as a diagnosis by itself.
There are a lot of diseases that can look like pemphigus complex disorders. Skin reaction to administered medications are the most common “look alike” disorder, but systemic lupus erythematosus, discoid lupus and skin cancers are other fairly common diseases that may be confused with pemphigus complex disorders. Even superficial pyodermas (hot spots) can look like pemphigus lesions. After physical examination, the veterinarian does a skin biopsy or refers the dog to a dermatopathologist for the biopsy. The biopsy determines histologic changes to reveal the subtype of pemphigus complex. Knowing the subtype is critical to treatment regime and determining a prognosis. To differentiate from other possible diseases such as lupus, an immunohistochemical or direct immunofluorescent testing may be done. Also blood tests for anti-plakin antibodies and desmoglein may assist in diagnosis.
Immunosuppression is essential in treating all the pemphigus complex diseases. Treatment of pemphigus erythematosus and pemphigus vegetans may not be necessary or is usually possible with topical corticosteroids or low to medium doses of prednisone. Tetracycline and niacinamide may also be necessary.
The treatment for pemphigus foliaceus and pemphigus vulgaris is aggressive immunosuppression using high doses of corticosteroids, either prednisone or dexamethasone. Secondary infections are common and antibiotic therapy is usually necessary. Special anti-bacterial baths may also be required using products such as Caphalexin. Occasionally steroids alone are unable to control the symptoms, or dogs are unable to tolerate high doses of corticosteroids due to their side effects, or in order to decrease the amount of corticosteroids necessary, azathioprine is used in addition to the corticosteroids. Corticosteroids have serious side effects and dogs taking them must be monitored closely. They may drink more water than normal and can develop urinary incontinence. Their appetites may be stimulated and metabolic changes may result making them more susceptible to weight gain. Long-term steroid use can bring on diabetes. The use of Azathioprine can cause problems with bone marrow production necessitating blood testing.
Treatment requires time and patience. Some cases will respond rapidly to therapy while others respond poorly depending upon the ability of medications to suppress the individual animal’s immune system. Another important factor is how well an individual tolerates the side effects of the medications. Dosages of medication are adjusted to reduce side effects while discouraging the return of skin lesions. Many dermatologists feel that pemphigus complex symptoms are more difficult to control if a relapse occurs.
Sunlight makes the symptoms worse, especially on de-pigmented areas of the nose. Dogs should be kept out of the sun or an SPF 15 sun block such as Veterinarian’s Best. Even x-rays can exacerbate the symptoms.
Treatment is usually for the life of the dogs. Approximately 50% of dogs with pemphigus foliaceus and pemphigus erythematosus can be kept symptom free. Other forms of the disease are more difficult to treat. Mortality rates are high for a variety of reasons. Because corticosteroids have serious side effects and can prove fatal, dogs must be monitored closely. The dogs have pain and open sores and must be bathed and cared for. This may be impossible for the owner of the dog with time restraints. Also the cost of veterinary care as well as the cost of drugs is prohibitive for some dog owners. Because the cost of treatment, extensive care of the animal, and suffering of the animal themselves is greater than some owners can shoulder, they elect to euthanize their dogs. Teamwork is important in treating pemphigus diseases. It is important not to be discouraged by failure to achieve a rapid response as this condition requires time and patience.
This article was reviewed by Larry Letche DMV for accuracy, 2012
Reviewed by author, 2016