9 year old, Male neutered, Pug, canine.
SOURCE/HISTORY: Diffuse crusting to pads and nail beds.Click here for the IDEXX Pathology Report on this case.
Non-haired and haired skin: There are marked intracorneal neutrophils and acantholytic cells. There are moderate dermal infiltrates of lymphocytes, plasma cells, eosinophils and neutrophils. There is superficial dermal fibrosis, acanthosis and hyperkeratosis.
Non haired and haired skin: Pododermatitis, pustular, marked, chronic, diffuse with acantholysis and moderate lymphoplasmacytic, eosinophilic and suppurative dermatitis
The microscopic appearance and clinical history are diagnostic for pemphigus foliaceus. Pemphigus foliaceous is an uncommon bullous autoimmune skin disease of dogs that affects the epidermis and hair follicles. Desmoglein 1 is a primary target autoantigen in canine pemphigus foliaceous, though other antigens may be targeted. The exact pathomechanism of vesicle and bulla formation is not known. However, loss of intercellular cohesion leads to acantholysis resulting in superficial vesicles and bullae. Transient superficial pustules develop in waves. Individual pustules may be large and vary in color from translucent to gray-white to yellow. Coalescence of pustules leads to visually distinct intact pustules or vesicopustules with irregular, asymmetric, polycyclic borders. Pustules frequently span multiple hair follicles, and multiple hairs may protrude from individual pustules. Animals may progress from absence of lesions to sudden development of dozens of pustules. Pustules quickly eventuate in thick adherent crusts with marked exfoliation. Rarely, erosions from ruptured pustules may exhibit targetoid or polycyclic patterns. Alopecia is variable. Generalized erythroderma may be seen. Photophobia may be noted that is unexplained. Pruritis is noted in less than one-half of affected dogs. The most common sites of involvement in the dog are the dorsal muzzle, nasal planum, pinnae, periorbital skin, and paw pads. The Bearded Collie, Akita, Chow Chow, Newfoundland, Schipperke, and Doberman Pinscher are genetically predisposed. More recently, the English Springer Spaniel, Chinese Shar-Pei, and Collie have also been shown to be at increased risk.
Jamie M. Bush, DVM, MS
Diplomate, American College of Veterinary Pathologists