Small Animal Dermatology, 3rd edition

chapter

Cutaneous Adverse Drug 17

Reaction, Erythema Multiforme,

Stevens–Johnson Syndrome, and

Toxic Epidermal Necrolysis

DEFINITION/OVERVIEW

 A spectrum of diseases and clinical signs that vary markedly in clinical appearance

and pathophysiology.

 Cutaneous adverse drug reaction (CADR) including exfoliative erythroderma: likely

that many mild drug reactions go unnoticed or unreported; thus, incidence rates for

specific drugs are unknown and most of the facts available on drug-specific reactions

have been extrapolated from reports in the human literature; frequency estimated at

2% (dog) and 1.6% (cat).

 Erythema multiforme (EM): most often idiopathic; previously thought to be associ-

ated with drug administration (controversial).

 Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN): separate

entities from EM; most likely drug-induced spectrum of dermatoses.

ETIOLOGY/PATHOPHYSIOLOGY

 CADR:
Drugs of any type: topical, oral, injectable
Exfoliative erythroderma: most often associated with shampoos and topical

medications

Can occur after the first dose or after weeks to months of administration of the

same drug; typically 5–36 days

Immunologic versus physiologic reaction

Genetic differences in susceptibility

May be dose related and predictable (e.g., corticosteroids and cutaneous atro-

phy) or idiosyncratic (immune mediated, often type 1 hypersensitivity)

Most common: sulfonamides, topicals, penicillins, cephalosporins (Fig-

ures 17.1–17.3).

 EM:
Keratinocyte is the target of an immune response resulting in apoptosis (indi-

vidual keratinocyte necrosis)

Reported triggers include antibiotics, food ingredients, infections (bacterial and

viral), and nutraceuticals (Figures 17.4–17.7)

Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.

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