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Dermatomyositis 246.e3

VetBooks.ir Diseases and Disorders

DERMATOMYOSITIS Skin biopsy from dog with dermatomyositis. Note clefting DERMATOMYOSITIS Classic alopecic tail tip of dogs with dermatomyositis.
and small hair follicles.

DERMATOMYOSITIS Adult dog with severe disease. Facial lesions are strongly DERMATOMYOSITIS A 6-month-old Shetland sheepdog showing facial lesions.
compatible with other immune-mediated skin diseases (e.g., lupus).

Initial Database • Muscle biopsy from temporal muscles reveals • Acute exacerbations
• Skin cytologic preparations to rule out myofibrillar degeneration and atrophy, with ○ Prednisone 1-2 mg/kg PO q 12-24h,
pyoderma and/or Malassezia overgrowth accumulations of mixed inflammatory cells. weaning down to an alternate-day regimen
• Skin scrapings and hair trichograms to rule • Neurologic examination is usually normal. based on a favorable response
out demodicosis (p. 1091) • Elevated concentrations of immunoglobulin ○ Use prednisone in conjunction with
• Wood’s lamp and dermatophyte culture to G (IgG) and circulating immune complexes pentoxifylline 15-25 mg/kg PO q 8-12h
rule out dermatophytosis may be seen. for severe acute exacerbations.
• Serum biochemistry profile may show ○ Focal lesions can be treated with topical
elevated creatine kinase; CBC and urinalysis TREATMENT 0.1% tacrolimus.
results unremarkable
Treatment Overview Chronic Treatment
Advanced or Confirmatory Testing This disease can be managed but not • Chronic management
• Skin biopsy for histopathologic evaluation cured. The primary goal is to minimize ○ Minimize exacerbations by avoidance of
(may be nondiagnostic in mild cases). scarring of facial skin and prevent/manage sunlight.
Characteristic hydropic degeneration in the debilitating myositis. No controlled studies ○ Omega-3 essential fatty acids and/or
basal cell layer, with a mild perivascular to exist to support that one treatment approach vitamin E 400-800 IU/dose PO q 24h
interstitial dermatitis. Follicular atrophy is superior to another. may be helpful, but it may take > 3
may be noted in chronic lesions. Vasculitis months to see benefit.
is occasionally noted. Acute General Treatment ○ Pentoxifylline 15-25 mg/kg PO q 8-12h
• Electromyograms are abnormal in cases • Lesions wax and wane, and response to alone; may take >3 months to see
with subclinical or clinical myositis and therapy is difficult to evaluate. improvement.
show positive sharp waves and fibrillation • Therapy is based on stage of the disease: ○ Cyclosporine (Atopica, Neoral) 5 mg/kg
potentials in muscles of the head and distal treatment of acute exacerbations or chronic PO q 12-24h as long-term therapy in place
extremities. management of glucocorticoids

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