Deadly dermatoses (Proceedings)
Deadly dermatoses are defined as
1. Lethal diseases for the pet.
Auto-immune skin diseases
Any auto-immune skin disease can ultimately become a deadly dermatosis based on the criteria listed above. Examples include pemphigus foliaceus, pemphigus vulgaris and systemic lupus erythematosus.
is the most common of our auto immune skin diseases. The term pemphigus comes from the Greek word for blister, and all pemphigus
diseases are blistering diseases. The hallmark of pemphigus diseases is acantholysis. Acantholysis is the process where keratinocytes
lose their later cellular attachments, leading to intraepidermal clefting. Initially, it was thought that neutrophils and
their mediators caused the clefts but we now realize that neutrophils invade the vesicle, leading to pustule formation. Many
breeds of dogs are predisposed to pemphigus foliaceus including Akitas, Dobermans, Chow-Chows, Shar-peis and Dachshunds. Pemphigus
foliaceus is typically found in middle aged dogs with a mean age of 4.2 years. Clinical signs of pemphigus foliaceus include
facial crusts, ulcers and often depigmentation of the planum nasale. There are usually large, intact pustules on the trunk
and face. Footpad hyperkeratosis and ulcerations are often noted, as are fevers and anorexia. Laboratory signs include a leukocytosis
with neutrophilia and hyperglobulinemia are often seen with cases of pemphigus foliaceus. In addition, pets may have anemia
of chronic disease or nonregenerative anemia. Cytologies of intact pustules may reveal hypersegmented neutrophils and acantholytic
to lytic cells.
is a more rare form of pemphigus and shows deeper clefting. Pemphigus vulgaris patients almost always (greater than 90%)
have oral ulcerations. The erosions that are seen are more severe than with pemphigus foliaceus, and this is a much more difficult
pemphigus to treat, often requiring much higher doses of steroid therapy initially to suppress the immune response.
Cutaneous and systemic lupus erythematosus
is another group of auto-immune skin diseases in our group of deadly dermatosis. Systemic lupus erythematosus is a multi-systemic
disease often with mucocutaneous lesions, polyarthritis, immune-mediated thrombocytopenia, auto-immune hemolytic anemia and
protein losing nephropathy. This disease is also known as the great imitator, due to the multitude of clinical signs that
may be present. Systemic lupus erythematosus is a result of a type III hypersensitivity reaction. Antibodies to nucleic acid
are a diagnostic hallmark for SLE (ANA positive). In one study of 75 cases of systemic lupus, the most common clinical signs
are polyarthritis in 91% of the cases, renal disease in 65% of the cases and mucocutaneous skin disorders in 60% of the cases.
Auto-immune hemolytic anemia was rare.
include a full spectrum of diseases from simple drug eruptions to more severe erythema multiforme to the most severe which
is toxic epidermal necrolysis. Drug eruptions like systemic lupus can be a great imitator and mimic many diseases, especially
autoimmune diseases. The most common drugs that are implicated in canine drug eruptions include sulfonamides and cephalosporins.
Drug eruptions are often targetoid lesions (bulls-eye) but can also be papular, vesicular and crusting.
Toxic epidermal necrolysis (TEN)
is the rarest of the drug eruptions but the most lethal. In the widespread necrosis of the skin, patients often have pyrexia,
anorexia, lethargy and pain.
Necrolytic migratory erythema (Hepatic Cutaneous syndrome)
is a syndrome that is usually seen in older animals. Hepatopathy, pancreatic or liver neoplasia are usually associated with
NME. Diabetes Mellitus is often seen, especially later in the course of NME. Secondary staph and/or malassezia infections
are often present. Necrolytic migratory erythema patients exhibit erythema, erosions, ulcerations and crusting often in the
mucocutaneous syndromes with footpad hyperkeratosis and ulcerations often leading to lameness.
can be a lethal disease due to extreme expense or extreme frustration of the owner. Demodicosis is seen in 2 populations
of canine patients. The younger genetic cases of demodicosis and older populations secondary to an immune-suppressing disease.
Sometimes demodicosis can be secondary to chronic allergic diseases due to long term steroid use and even immune dysfunction
from the chronic allergic disease.
1. Mass cell tumors
Cutaneous T-Cell lymphoma
is a proliferation of T-lymphocytes that have an epidermal affinity often leading to micro abscesses in the epidermis called
Pautrier's micro abscesses. Many forms of T-cell are seen in the dog including a generalized erythema scaling, mucocutaneous
depigmentations with erosions, crusting plaques, nodules to frank tumors.
is a recently described syndrome in older cats that have a rather classic shiny skin with exfoliated alopecia. These cats
often have weight loss and/or anorexia and ultrsonographic examination will usually reveal pancreatic carcinoma.