Pemphigus in Dogs
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.
"Viral infections and ultraviolet (UV) light exposure
can trigger inflammation in the skin,
which can make a dog more likely to develop
an autoimmune reaction such as pemphigus."
Exogenous causes of pemphigus include factors outside of the dog that can trigger an overactive immune response. Possible exogenous causes of pemphigus include anything that can trigger unusual inflammation. Viral infections and ultraviolet (UV) light exposure can trigger inflammation in the skin, which can make a dog more likely to develop an autoimmune reaction such as pemphigus. 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.
Many 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 often vary in their clinical appearance. The three most common types of pemphigus are pemphigus foliaceus, pemphigus vulgaris, and pemphigus erythematosus.
Pemphigus Foliaceus (PF) – Pemphigus Foliaceus is the most common autoimmune skin disease in dogs and cats. PF 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 commonly 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 more mild in appearance. Predisposed breeds include German Shepherds, Collies, and Shetland Sheepdogs.
Pemphigus Vulgaris (PV) – 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 often are seen at the edges of the lips and eyes, though they often will spread to other areas of the body over time.
How is pemphigus diagnosed?
The diagnosis of pemphigus requires a skin biopsy. Your veterinarian will obtain a small sample of tissue from a skin lesion, using an instrument called a punch biopsy. This instrument allows your veterinarian to remove a small, circular plug of skin. Depending on your pet’s temperament and the site of his lesions, this procedure may be performed with the aid of a local anesthetic injection or under general sedation/anesthesia.
"The diagnosis of pemphigus requires a skin biopsy."
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 at a later date to have sutures removed. If your veterinarian used dissolving sutures, the sutures will dissolve on their own in the coming weeks.
After removal, 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 be able to determine whether your dog has DLE (discoid lupus erythematosus).
How is pemphigus treated?
Pemphigus is an autoimmune disease. Therefore, 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 lifelong, therapy in order to control signs of pemphigus. In addition, frequent rechecks will be needed to monitor the response to treatment and also to ensure that the patient is not developing negative side effects from medications.
What is my dog’s prognosis?
The prognosis for pemphigus varies depending on the type of pemphigus that is present.
Pemphigus vulgaris 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 the less-severe variants of pemphigus.
Pemphigus erythematosus, in contrast, carries 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, the most common form of pemphigus, also carries a relatively good prognosis, though the individual response to treatment can vary. Some dogs with PF will achieve rapid control of clinical signs with medication and then be able to be gradually weaned off medication completely. Many dogs will respond well, but require lifelong therapy. Unfortunately, some cases may be resistant to treatment and the prognosis in these cases is guarded.
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