Page 1486 - Clinical Small Animal Internal Medicine

1424 Section 12 Skin and Ear Diseases

should be taken from an erythematous area of skin adja-
VetBooks.ir cent to an ulcer. The clinician should take care to avoid
sampling eroded or ulcerated skin. Ulcerated skin has
less diagnostic value. The skin should not be scrubbed or
clipped prior to procuring the biopsy. Care should be
taken to include only abnormal skin in the biopsy. The
histopathology reveals diffuse necrosis of the epidermis
with minimal dermal inflammation.
Clinical differential diagnoses include first‐degree
burn and toxic shock syndrome.
The identification and removal of a possible underly-
ing cause are important in the management of TEN;
however, many cases are idiopathic. The most common
precipitating factor is drugs. Other less common triggers
include vaccination, neoplasia, infections, and preg-
nancy. Wound care and general supportive care are criti-
Figure 162.1 Less than 1‐year‐old, male, intact collie with cal to attempt to prevent sepsis. The use of glucocorticoids
nonpruritic alopecia associated with dermatomyositis. is controversial but ciclosporin and IVIG have been used
with beneficial results in some cases.
and necrotizing dermatoses, superficial necrolytic der- Complications can include severe pyoderma and
matitis, and zinc‐responsive dermatosis. sepsis. The prognosis is guarded.
The identification and removal of the possible under-
lying cause are important in the management of EM;
however, some cases are idiopathic. Triggering causes Cutaneous Lupus Erythematosus
may include drugs, bacterial infections, Pneumocystis
pneumonia, parvovirus, food, neoplasia or possibly her- Discoid Lupus Erythematosus
pesvirus. Mildly affected individuals may experience
resolution of disease without additional therapy. Other Discoid lupus erythematosus (DLE) is a fairly common
patients may need immunosuppressive therapy such as photoaggravated or perhaps even photoinduced, depig-
glucocorticoids, azathioprine, ciclosporin, and/or intra- menting autoimmune skin disease. It affects middle‐
venous immunoglobulin therapy (IVIG) (see Table 162.1). aged dogs, and collies, Shetland sheepdogs, German
Complications can include secondary pyoderma. The shepherd dogs, and Siberian huskies are predisposed.
prognosis depends on the severity of the lesions and One case of generalized DLE has been reported in a
response to therapy. Chinese crested dog. DLE has rarely been reported
in cats. Sex and age predilections have not been
substantiated.
Toxic Epidermal Necrolysis The disease is characterized by depigmentation and
loss of cobblestone architecture of the nasal planum
Toxic epidermal necrolysis (TEN) is a severe vesiculob- (Figure 162.2). Erosions and crusting may also develop.
ullous disorder affecting the skin and oral mucosa of While the nasal planum is most typically affected, lesions
dogs and cats. Dogs and cats of any age, sex or breed can may also be found extending proximal to the nasal
be affected. planum, around the eyes, around the mouth, on the
Toxic epidermal necrolysis is characterized by general- genitals and distal extremities. Oral ulceration may also
ized erythematous or purpuric patches, and skin ulcera- be present.
tion involving more than 30% of the body. Systemic signs Diagnosis is based on history, physical examination,
(pyrexia, lethargy, depression, and/or anorexia) typically exclusion of systemic involvement, and skin biopsy find-
accompany the skin lesions. ings. The clinician should select a site of recent depig-
Toxic epidermal necrolysis is often thought of as a mentation for punch biopsy. Lesions with severe crusting,
severe variation of EM although some clinicians con- ulceration or scarring should be avoided. The skin should
sider the two as separate diseases. It is generally differen- not be scrubbed or clipped prior to procuring the biopsy.
tiated from EM based on the severity of skin lesions and Care should be taken to include only abnormal skin in
the percentage of the body that is affected. the biopsy. Histopathology reveals lymphocytic interface
The disease is diagnosed based on history, physical dermatitis. Direct immunofluorescence can further
examination, and skin biopsy findings. Punch biopsies support the diagnosis.