Page 188 - WSAVA2018
P. 188

 25-28 September, 2018 | Singapore
WSV18-0083
SVA DERMATOLOGY (SIMULTANEOUS TRANSLATION INTO MANDARIN CHINESE)
DIAGNOSIS AND MANAGEMENT OF COMMON IMMUNE-MEDIATED SKIN DISEASES
M. Siak1
1Western Australian Veterinary Emergency and Specialty WAVES, Veterinary Dermatology, Western Australia, Australia
Introduction
In this presentation, we will cover two of the most common autoimmune skin diseases affecting dogs and cats: Pemphigus foliaceus and discoid lupus erythematosus.
1. Pemphigus foliaceus
Canine Pemphigus encompasses four variants; pemphigus foliaceus, pemphigus vulgaris, pemphigus vegetans and paraneoplastic pemphigus. Pemphigus foliaceus is the most common variant and also the most common autoimmune skin disease affecting dogs and cats.
Cats
Lesions most commonly affect the face, ears and feet and are typically bilateral and symmetrical. Claw folds may reveal suppurative exudation. Peri-mammary crusting is considered highly suspicious for Pemphigus foliaceus.
Clinical differentiation between Pemphigus foliaceus and bacterial pyoderma
       Pemphigus foliaceus
  Bacterial pyoder- ma
  Lesion symmetry
    Yes
   No
  Distribution
  Mainly head/ face and feet
 Mainly ventrum and trunk
  Nasal planum involvement
   Yes
  No
  Footpad involvement
    Yes
   No
  Pustules
  Large, panfol- licular, flaccid and conflu- ent Usually same stage of develop- ment (devel- op in waves)
 Single follicular and turgid Various stages of devel- opment
  Irregular, polycyclic or annular pustules
   Yes
  No
  Epidermal collarettes
   Few
  Many
  Palisading crusts
    Yes
   No
  Paronychia and peri-mammary crusting
   In cats
  Uncommon
 Pathomechanism:
Anti-keratinocyte antibodies induce loss of cohesion (acantholysis) between keratinocytes resulting in formation of pustules that rapidly progress to erosions, crusts and alopecia. In the dog, the major autoantigen is desmocollin 1. Pemphigus foliaceus can occur spontaneously or secondary to triggers such as drugs, vaccine or ultraviolet light.
Signalment:
· Chow Chows and Akitas are predisposed
· Typically middle age
Diagnostic approach:
Cytology
An easy test to increase suspicion for pemphigus foliaceus is to perform cytological evaluation of an intact pustule. The typical findings are “rafts” of acantholytic keratinocytes with non-degenerated neutrophils with or without eosinophils.
The presence of acantholytic keratinocytes does
not confirm the dog/cat has pemphigus foliaceus. Acantholysis can also occur secondary to other diseases such as pustular dermatophytosis (especially due to Trichophyton mentagrophytes) and bacterial diseases (i.e. bullous impetigo and exfoliative superficial pyoderma).
Histopathology
Biopsies of intact pustules and/or crusts will reveal subcorneal pustules with acantholytic keratinocytes. Special stains (e.g. Gram stain for bacteria and PAS for fungi) can rule out infectious causes for the acantholysis. Tissue cultures should be performed to definitely rule out infections.
· No sex prediction for dogs; possibly more common in female cats
Clinical signs:
The characteristic lesion in both dogs and cats is a pustule, which evolve rapidly into erosions, crusts and alopecia. Lesions often develop in waves and may wax and wane. Depigmentation affecting nasal planum and footpads are common.
Distribution:
Dogs
The face is the most common initial site of lesions. The disease progresses to affect the dorsal muzzle, nasal planum, peri-ocular areas, ears, trunk and footpads. Lesions are typically bilateral and symmetrical but can be localised (e.g. face or clawfolds). Affected dogs may show pruritus and systemic symptoms such as anorexia and lethargy. Weight loss may be present in severe cases.
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43RD WORLD SMALL ANIMAL VETERINARY ASSOCIATION CONGRESS AND 9TH FASAVA CONGRESS





































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