Canine Toxic Epidermal Necrolysis

Toxic epidermal necrolysis (TEN) is a life-threatening ulcerative skin disease that involves the mucous membranes and skin surfaces and causes tissue death (necrosis). Necrosis of the mucosa of the trachea, large bronchi, pharynx and esophagus can also occur. What causes the disease is unknown. In dogs, the disease is often associated with some predisposing conditions, such as staphylococcal infection, drug administration, cancers and metabolic disorders. While the exact agents of initiation of TEN are not yet known, recent sources agree that massive death of keratinocytes initiated by toxic T-cells and mononuclear cells might be a factor.3

The disease is marked by large, painful, ulcerative areas on any part of the body, but particularly on the head, footpads, and mucocutaneous junctions (transitional zones between the skin and mucous membranes in the mouth, nose, etc.). Toxic epidermal necrolysis can mimic a massive second-degree burn. The necrotic outer layer of the skin (epidermis) separates from the dermis to form variably sized blisters, which rupture, forming ulcers. Ulceration often induces a secondary dermatitis. Fever, loss of appetite, shock, and even death may be a consequence of TEN.



The diagnosis is based on history, clinical signs and skin biopsy. Biopsy of red, non-ulcerated areas reveals acute necrosis of the entire thickness of the epidermis and the formation of subepidermal blisters (vesicles). Additional tests may be required to include a hemogram, serum chemistry profile and analysis of the urine. Common abnormalities include increase in the number of white blood cells (leukocytosis), electrolyte abnormalities that can cause heart failure, low level of total serum protein (hypoproteinemia), and abnormal kidney function. Supportive topical therapy with astringents (remedies that have a 'binding' action on tissue), intravenous fluid therapy, and systemic antibiotics usually is indicated. Corticosteroids use in the treatment of TEN is controversial. The underlying disease must be identified and treated if TEN is to resolve. The prognosis is poor as toxic epidermal necrolysis has a high mortality rate due to fluid and electrolyte loss through the damaged skin.

References

  1. Nesbitt G.E. & Ackerman L.J. Canine Immune-Mediated Skin Diseases. In: Canine and Feline Dermatology: Diagnosis and Treatment. Veterinary Learning Systems, Trenton, New Jersey
  2. Results AFIP Wednesday Slide Conference - No. 27 8 May 1996, Division of Comparative Pathology, John Hopkins University, MD
  3. Skin Diseases of the Dog and Cat: Clinical and Histopathologic Diagnosis. Thelma Lee Gross, Peter J. Ihrke, Emily J. Walder, Verena K. Affolter




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