Affects: Dogs
Autoimmune skin diseases occur when the immune system of an infected animal attacks its own skin. In dogs, autoimmune skin diseases are usually not detected until visible symptoms appear, which differs from detection in humans who are able to verbally express their concerns. Genetics, nutrition, and external environmental factors all collectively contribute to increasing the probability an autoimmune skin disease occurring. The severity of symptoms varies based on the specific disease present and how far it has progressed. Diagnosis often requires the onset of visible symptoms and for a biopsy to be performed. For many diseases, the condition itself cannot be cured, but a veterinarian can prescribe medications and other forms of treatment to help manage the symptoms of the dog.
Diagnosis: Since many autoimmune skin diseases have similar symptoms and usually affect the oral cavity, a biopsy must often be performed in order to correctly diagnose the disease. Due to the wide scale of clinical symptoms that can be present, along with the diverse variations of skin autoimmune dermatoses, a single symptom will more than likely not lead to a diagnosis. Instead, the results of the biopsy combined with the canine's history and other clinical signs can help in confirming the diagnosis of the disease. Breed predisposition and the age of the dog can also be indications of the various possibilities of autoimmune skin diseases. Some common symptoms that can be used to lead to a confirmed diagnosis include alopecia, crusting, ulcerations, vasculitis, and many more.
Histopathology evaluations can be done by extracting areas of the skin that show indications of being affected, such as taking biopsies of lesions, pustules, and sites of crustation. These tissue samples would then be typically examined under a microscope, where a clinician will form a conclusive diagnosis based on the observed cellular structures and abnormalities. Additionally, other tests such as antinuclear antibody tests (ANA) and complete blood count with white blood cell differential tests can be used to gather more information.
For Pemphigus vulgaris, after the skin begins to separate, Nikolsky's sign can be useful to help diagnose the disease. This involves placing pressure along the edge of a blister and observing if the skin separates further and if the blister increases in size. However, to diagnose the disease with complete certainty, biopsies must be taken from the edge of the blisters. The tissue sample must then be analyzed using a direct immunofluorescence technique and analyzed microscopically. The direct immunofluorescence technique should be used instead of indirect, as the results may be inaccurate before the disease has progressed to a certain point.
Treatment: For most autoimmune skin diseases, it is imperative to begin treatment as early as possible, as the progression of the disease can lead to severe complications and even death. Treatment for many diseases usually involves the use of immunosuppressants such as glucocorticoids. The immunosuppressants aid in suppressing the reaction of the immune system fighting against the body's healthy cells and tissues. This is done by the inhibition of calcineurin, an enzyme that controls and activates T-cell production. Without the consistent production of T-cells, a decrease of autoimmune activity can be observed, leading to less severe symptoms and potential remission of autoimmune diseases.
When treatment is first started for Pemphigus vulgaris, the dog will usually be given the corticosteroid prednisone for a limited time. This will be administered orally, and the amount given can vary between 1.5 and 13.3 milligrams for every kilogram of the dog's weight. This amount will continue until symptoms begin to subside. Afterward the dose will be lowered, and other medications will be used. The condition cannot be cured, so the dog will require immunosuppressants and steroids for the duration of its lifespan. The specific immunosuppressants used generally include cyclophosphamide, methotrexate, or azathioprine. Antibiotics may also be used to help reduce the risk of infection.