Small Animal Dermatology, 3rd edition

CHAPTER 29 KERATINIZATION (CORNIFICATION) DISORDERS 437

 Cytology of skin surface: bacteria folliculitis and/orMalasseziadermatitis.

 Examination of plucked hairs: macromelanosomes and structural abnormalities in

follicular dysplasia and color dilution alopecia.

 Dermatohistopathology required for diagnosis.

 Genetic testing available for select disorders; Antagene-Lyon, France; Medical Genet-

ics Department at The University of Pennsylvania School of Veterinary Medicine,

USA.

THERAPEUTICS

 These disorders are characterized by damage to the integrity of the epidermal lipid

barrier which results in accelerated TEWL; the skin attempts to heal the flawed barrier

and produce more lipid by becoming hyperplastic and hyperkeratotic; harsh topicals

may alter the “healing response” of the epidermis.

 Therapeutic focus is on identification and correction of the specific defect when pos-

sible as a means to restore the damaged epidermal lipid barrier.

 Frequent and adequate topical therapy is the cornerstone of proper treatment.

 Underbathing, rather than overbathing, is a common error.

 Diagnose and control all treatable primary and secondary diseases.

 Recurrence of secondary infections may require repeated therapy and further diag-

nostics.

 Maintaining control is often life-long.

 Recent treatment emphasizes restoring epidermal barrier integrity and function.

Topical Therapy

 Shampoos:
Contact time: 5–15 minutes; greater than 15 minutes discouraged: may result in

epidermal maceration, loss of barrier function, and excessive epidermal drying

and irritation

Hypoallergenic: useful only in mild cases of dry scale and to maintain secondary

exfoliation after the primary disease has been controlled

Sulfur/salicylic acid: salicylic acid is keratolytic (aids desquamation by decreas-

ing skin pH which subsequently increases water absorption in the stratum

corneum); sulfur is keratolytic, keratoplastic, and bacteriostatic; moderately

scaly patient; not overly drying

Benzoyl peroxide: strongly keratolytic and antimicrobial; may cause irritation

and severe dryness; best for recurrent bacterial infection and/or greasiness

Ethyl lactate: antimicrobial; not as irritating or drying as benzoyl peroxide; most

useful for moderate bacterial folliculitis and dry scale

Chlorhexidine: antimicrobial; mildly drying; useful for moderate bacterial folli-

culitis andMalasseziadermatitis; often combined with antifungal agents (e.g.,

miconazole, ketoconazole)