What is pemphigus?
Pemphigus is an autoimmune skin disease in which the body’s immune system attacks the connections between its own skin cells.
What causes pemphigus?
There are three possible causes of pemphigus: endogenous (internal), exogenous (external), and idiopathic (unexplained).
Endogenous cases of pemphigus are caused by some factor within the dog. These factors may include the dog’s breed or a genetic predisposition. Some dogs have defects in their immune function, making their immune system more likely to mount an attack against normal cells. Pemphigus may also be triggered by an underlying medical condition, such as chronic skin allergies or cancer.
Exogenous causes of pemphigus include factors outside the dog that can trigger an overactive immune response. Possible exogenous causes of pemphigus include anything that triggers unusual inflammation, such as viral infections and ultraviolet (UV) light exposure. Drug reactions can also trigger pemphigus, either as a short-term allergic reaction to the drug itself (which will resolve once the drug leaves the system) or by creating lasting changes in the immune system of predisposed patients.
Most cases of pemphigus are idiopathic in nature. Idiopathic means that no cause can be found, despite extensive testing. As frustrating as it may be for veterinarians and pet owners, these cases “just happen” and we do not know why.
What are the signs of pemphigus?
There are multiple types of pemphigus, and these different types vary in their clinical appearance. The three most common types of pemphigus are pemphigus foliaceus, pemphigus vulgaris, and pemphigus erythematosus.
Pemphigus Foliaceus: Pemphigus foliaceus is the most common autoimmune skin disease in dogs and cats. It is often observed in middle-aged and older patients. Pemphigus foliaceus typically causes hair loss, scabs, and ulcers (open sores) around the head, face, and ears. These lesions may become more widespread over time, covering other parts of the body. Pemphigus foliaceus is most seen in chow chows, akitas, cocker spaniels, Labrador retrievers, dachshunds, and English bulldogs, though other breeds may also develop this condition.
Pemphigus Erythematosus: This form of pemphigus is similar in appearance to pemphigus foliaceus, although cases are often milder in appearance. Predisposed breeds include German shepherds, collies, and Shetland sheepdogs.
Pemphigus Vulgaris: This form of pemphigus attacks the deepest layers of the epidermis, making it the most severe type of pemphigus. Pemphigus vulgaris causes the formation of fluid-filled blisters, known as vesicles. These vesicles often rupture, leaving painful ulcerative lesions. Lesions are often seen at the edges of the lips and eyes, though they will often spread to other areas of the body over time.
How is pemphigus diagnosed?
The diagnosis of pemphigus requires a skin biopsy. Your veterinarian will use a biopsy punch to remove a small, circular plug of skin from a skin lesion. Depending on your pet’s temperament and the site of the lesions, this procedure may be performed with a local anesthetic injection or under general sedation/anesthesia.
Once the skin biopsy sample has been removed, the biopsy site will be closed with sutures. Depending on the type of suture used, your veterinarian may have you return later to have the sutures removed. If your veterinarian used dissolving sutures, the sutures will dissolve on their own in the coming weeks.
The skin sample will be sent to a pathologist for analysis. By processing the skin sample and examining it under a microscope, the pathologist will determine whether your dog has pemphigus.
How is pemphigus treated?
Pemphigus is an autoimmune disease, so treatment requires suppression of the immune system. Your pet will be treated with corticosteroids (such as prednisone) or other immunosuppressive drugs, such as azathioprine, chlorambucil, or cyclosporine.
Patients will require long-term, sometimes life-long, therapy to control signs of pemphigus. In addition, frequent rechecks will be needed to monitor the response to treatment and to ensure that the patient does not develop negative side effects from medications. The goal is to use the lowest effective dose of medication to maintain remission of clinical signs.
What is my dog’s prognosis?
The prognosis for pemphigus varies, depending on the type of pemphigus that is present.
Pemphigus vulgaris (PV) is a serious condition with a poor prognosis. Despite therapy, this disease is often fatal, due to its widespread effects on the skin. Fortunately, PV is far less common than other variants of pemphigus.
Pemphigus erythematosus (PE) has a good prognosis. While the skin lesions may be uncomfortable and unattractive, they rarely affect the dog’s overall health. Dogs with PE usually respond very well to treatment.
Pemphigus foliaceus (PF), the most common form of pemphigus, also carries a relatively good prognosis, though the individual response to treatment can vary. Some dogs with PF achieve rapid control of clinical signs with medication and then can be gradually weaned off medication completely. Many dogs respond well but require life-long therapy. Unfortunately, some cases may be resistant to treatment and the prognosis in these cases is guarded.
