Pemphigus foliaceus (pem-fi-gus foli-a-shus) is an auto immune disease that affects humans and dogs and, to a lesser extent, cats and horses.
In horses, it is characterized by primary lesions that often begin on the head and lower extremities; secondary lesions spread to other areas, with an exudate that dries to a crust. There may be extensive edema (swelling) in the legs and abdomen (called “ventral” edema).
Equine pemphigus foliaceus (EPF) is considered rare and signs and symptoms may resemble those of other conditions such as insect bite allergies (crusty lesions), pigeon fever (ventral edema) or other skin conditions.
The primary way to diagnose EPF is by punch biopsy of the skin which is examined by a veterinary pathologist. The pathologist looks for changes consistent with this diagnosis, while also ruling out other causes.
Horses with EPF may also have systemic signs of illness – fever, depression, perte d'appétit, lethargy and weight loss. The skin may be painful to touch and swelling can make it difficult to walk or lie down.
Full article can be found on: http://desertequinebalance.blogspot.com/2009/11/equine-pemphigus-foliaceus.html