Small Animal Dermatology, 3rd edition

314 DISEASES/DISORDERS

DIAGNOSTICS

 CBC: nonregenerative anemia may occur with severe disease.

 Serum chemistries: creatine kinase may be normal or slightly high.

 ANA titers and lupus erythematosus tests negative.

 EMG: abnormalities in affected muscles; fibrillation potentials; bizarre high-

frequency discharges; positive sharp waves.

 Muscle biopsy: difficult because pathologic changes may be mild, multifocal, or (in

early states) absent; ideally, use EMG to select affected muscles; otherwise, biopsy

atrophied muscles:

Variable multifocal accumulations of inflammatory cells, including lymphocytes,

macrophages, plasma cells, neutrophils, and eosinophils

Myofibril degeneration characterized by fragmentation, vacuolation, and

increased eosinophilia of the myofibrils

Myofiber atrophy and regeneration.

 Skin biopsy: choose papules, vesicles, or lesions that show alopecia and erythema;

avoid infected and scarred lesions:

Scattered necrotic basal cells (colloid bodies) or vacuolated individual basal cells

Occasionally, vesicles that contain small amounts of RBCs

Superficial, mild, diffuse dermal inflammatory infiltrates composed of lympho-

cytes and histiocytes with variable numbers of mast cells and neutrophils (espe-

cially perifollicular)

Follicular basal cell degeneration and follicular atrophy

Secondary epidermal ulceration and dermal scarring

Combination of perifollicular inflammation, epidermal and follicular cell degen-

eration, and follicular atrophy strongly supports the diagnosis.

THERAPEUTICS

 Nonspecific symptomatic therapy, including gentle soakings of crusts and treatment

of secondary pyoderma.

 Avoid activities that may traumatize the skin.

 Keep indoors during the day to avoid exposure to intense sunlight.

 Estrus may exacerbate the disease; neutering intact females is recommended.

Drugs of Choice

 Therapeutic efficacy of medical treatment can be difficult to assess because the disease

tends to be cyclic and is often self-limiting.

 Vitamin E: 100–400 IU PO BID to q24h.

 Prednisolone: 1–2 mg/kg PO BID until remission; then alternate-day administration;

use the lowest dosage possible for long-term control.