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One of the more common presentations in autoimmune dermatoses in canines is the pemphigus complex. Unlike in humans, the most common presentation in dogs is pemphigus foliaceous or pemphigus erythematosus. Most treatments involve immunosuppressive therapies including corticosteroids and chemotherapeutic agents.
Pemphigus foliaceous is seen in dogs and in cats. Usually this is pustular epidermitis. Pustules and crusts are seen in the ears, ear margins, perioral, periauricular, dorsal muzzle, planum, and nailbed. The most common presentation in felines is a paronychia pyonychia.
A photograph of intact pustules was shown but more commonly generalized crusting is seen. Dr. Messina then showed a photograph of a German shorthaired painter with generalized crusting who was septic upon presentation. Currently the dog is in remission on every other day corticosteroid therapy.
Skin biopsies are done to confirm the diagnosis. (Occasionally a direct smear of a pustule will show acantholytic cells). On CBC there is a leukocytosis with mature neutrophils. On histopathology is a pustular epidermitis with acantholysis in the superficial epidermis.
The pemphigus erythematosus variant usually presents with some depigmentation of the planum nasale. Clinically the crusting is similar to that seen in P. foliaceous. A photo of a Chow-Chow with extensive crusting was shown with depigmentation of planum nasale and loss of the architecture of the planum nasale (similar to that seen in DLE and SLE). Other photos showed involvement of the foot pad and nail bed.
In P. erythematous, the ANA is positive 50% of the time. The histopathology shows a pustular epidermitis with acantholysis, an interface dermatitis and some dyskeratosis.
P. vulgaris is not as common in canines. It usually presents with involvement of mucocutaneous regions though there may be foot-pad involvement. Clinically it is similar to bullous pemphigoid and SLE.
A photo of an upper lip of a dog showing ulcerations demonstrated the most common finding in P. vulgaris. On histopathology, suprabasilar pustules with acantholysis is seen.
A photo of a dog with P. vegetans (very rare) was shown. The lesions are vegetative and verrucous and resemble papillomovirus in dogs.
The treatment of these disorders is immunosuppressives. Prednisone and prednisolone are used in combination with azathioprine. (Azathioprine is too bone marrow toxic for cats and chlorambucil is substituted.) Six to eight weeks of aggressive immunosuppresive therapy is generally needed to bring cases to clinical remission with slow tapering.
Next, Dr. Messina spoke on systemic and discoid lupus erythematous in dogs. The SLE dogs are usually much sicker on presentation with multi-organ system involvement.
DLE is more common than SLE. Like P. erythematous, there is depigmentation of the planum nasale leading to ulceration. Eyelids, lips, and foot pads can be involved. Sunlight exacerbates this condition so sunblocks are used. (Gels are best and Bullfrog is a favorite brand for dogs.)
A photograph was shown of a dog with DLE showing loss of pigmentation of the planum. The nose becomes smooth and shiny with loss of architecture and crusting. Some areas become ulcerated.
In SLE, there are vasculitides. There is ulcerative stomatitis, and foot pad ulcerations. A photo was shown with interdigital ulcerations. There can be onychorrhexis with sloughing of the nails. Depigmentation as in DLE is also seen. Paronychia pyonychia is also common. There can be distal limb edemas from vasculitis.
The ANA in DLE is only 5% positive however these dogs are more likely to progress to SLE. On histopathology of DLE, there is a lichenoid interface dermatitis, a thickened basement membrane zone, hydropic degeneration and colloid bodies and pigmentary incontinence.
In SLE, 85-90% of patients are ANA positive. On histopathology are all the signs of DLE with additionally a leukocytoclastic vasculitis and mononuclear panniculitis.
Treatment is immunosuppressives and sunscreen. DLE has a favorable prognosis. SLE has a variable prognosis based on the organ systems involved.
(During the Q and A session, it was noted that German Shepards are the most common breed affected by DLE. Pemphigus is seen most commonly in Cocker Spaniels.)
This meeting was supported by an educational grant from Berlex dermatology.
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