Any primary disease of the skin where there is degeneration or necrosis of the epidermis, dermis or subcutis without a recognisable primary inflammatory pattern. Familial dermatomyositis and vasculitis have secondary necrosis, but are primary inflammatory diseases.
Ischemic, thermal, actinic, traumatic, toxic compounds, and electrical causes potentially result in necrosis.
Actinic/solar burns.
There are several syndromes where solar burns or actinic injury occurs. These include
- Photosensitization due to photodynamic agents as in porphyia
- Photoallergy
- Direct solar (actinic) damage
Ischemic dermatopathy
Ischemic dermatopathy occurs because of a lack of blood flow to the affected area of skin. The underlying cause is not evident, but is assumed to be vasculitic in origin.
It can be local (after vaccination) or generalised (affecting the ears, face, tip of tail, and feet).
Histologically, the lesions include follicular atrophy, a cell-poor lymphocytic interface dermatitis, dermal oedema or mucin deposition, dermal collagen eosinophilia and vascular walls have a smudgy appearance.
Those cases related to vaccine panniculitis are secondary to a single nodular panniculitis (see Inflammatory skin disease: Panniculitis)
Idiopathic generalised ischemic dermatopathy is assumed to have an immune mediated mechanism that has an environmental trigger such as infections, vaccines, drugs, UV exposure and stressful events.
Backel KA, Bradley CW, Cain CL, Morris DO, Goldschmidt KH, Mauldin EA. Canine ischaemic dermatopathy: a retrospective study of 177 cases (2005-2016). Vet Dermatol. 2019; 30: 403-e122.
Thermal burns
Burns of skin are often identified after contact with a hot surface. The exhaust system of vehicles, especially catalytic converters, water from a hose left in the sun, a heating pad at surgery are common culprits.
Garden hose scalding syndrome
Quist et al (2102) reported on dogs that were hosed with water from hoses left in the sun. The dogs had linear burns of the skin on their dorsum. Histological lesions included epidermal and dermal necrosis with occasional fibrinoid necrosis of vessel walls, vasculitis and intravascular thrombosis.
Quist EM, Tanabe M, Mansell JE, Edwards JL. A case series of thermal scald injuries in dogs exposed to hot water from garden hoses (garden hose scalding syndrome). Vet Dermatol. 2012; 23: 162-166, e33.
Trauma
Acral Lick Dermatitis ('lick granuloma')
Electical burns
Pressure injury
Toxic substances