Autoimmune skin disease of large animals.

This paper reviews existing literature on the autoimmune skin disease Pemphigus foliaceus observed in horses and shares case studies of two horses suspected of having autoimmune skin conditions. While Pemphigus foliaceus is recognized, the exact role of autoantibodies in the clinical syndrome is not well known. The disease is associated with dermatitis and the creation of intercellular blisters that expose deeper skin layers to pathogens.

Overview of Pemphigus Foliaceus

• The study focuses on Pemphigus foliaceus, an autoimmune disease of the skin that creates intercellular blisters by detaching cells thought to be due to an immunoglobulin-mediated phenomenon.
• As blisters rupture from physical trauma, deeper skin layers are exposed to pathogenic bacteria and environmental insults.
• The disease is found in horses of different breeds, such as Standardbred, Morgan, and Appaloosa and affects animals ranging in age from 4 months to 7 years.

Case 1: Female Quarter Horse

• The first reported case involves a 5-year-old female quarter horse that presented ulcerative lesions on its lips, eyes, vulva, and tongue. Initial antibiotic and steroid treatment were ineffective.
• Microscopic examinations revealed separation of the dermal and epidermal layers with subepidermal bullae, indicating a significant skin ailment.
• Despite increased dosages of treatment, the horse’s condition worsened, progressing to lameness, fever, and eventually pleuritis and laminitis leading to euthanization.
• The findings closely resembled those of a disease known as bullous pemphigoid described in dogs and humans.

Case 2: Arabian Gelding

• The second case includes a 6-year-old Arabian gelding who experienced a painful skin disease of the distal limbs, with symptoms including hair loss, swelling, scaling, and ulceration.
• Microscopic examinations confirmed the presence of acantholysis (loss of cell adhesion), cleft, and blister formation in the superficial epidermis.
• The condition resulted in inflammations composed of neutrophils, lymphocytes, macrophages, and eosinophils.

Overall, this study provides important insight into the Pemphigus foliaceus disease in horses and emphasizes the need for more research to better understand its pathogenesis and successful treatment.