Acne – Feline
Acne is inflammatory dermatitis affecting the chin and lips. Its symptoms may be recurrent or persistent and its precise etiology is unknown.
SIGNS
Cats may have a single episode, a life-long recurrent problem, or a continual disease.
The frequency and severity of each occurrence vary with the individual.
Comedones, mild erythematous papules, serous crusts, and dark keratin debris develop on the chin and less commonly on the lips.
Swelling of the chin.
Severe cases—nodules, hemorrhagic crusts, pustules, cysts, fistulae, severe erythema, alopecia, and pain.
Pain is often associated with bacterial furunculosis.
CAUSES & RISK FACTORS
Precise etiology unknown; may be a disorder of keratinization, poor grooming, abnormal sebum production, immunosuppression, viral infection, or stress.
DIAGNOSIS
DIFFERENTIAL DIAGNOSIS
Bacterial folliculitis
Demodicosis
Malassezia infection
Dermatophytosis
Neoplasia of sebaceous or apocrine glands
Eosinophilic granuloma
Contact hypersensitivity
DIAGNOSTIC PROCEDURES
Skin scrapings—demodicosis.
Fungal culture—dermatophytosis.
Cytology—bacteria, Malassezia.
Biopsy—rarely needed; necessary in selected cases to characterize changes such as cystic follicles, to differentiate acne from other diseases such as demodicosis, infections (bacterial, yeast, or dermatophytes), or to diagnose neoplasia.
PATHOLOGIC FINDINGS
Mild disease—follicular distention with keratin (comedo), hyperkeratosis, and follicular plugging.
Severe disease—mild to severe folliculitis and perifolliculitis with follicular pustule formation leading to furunculosis and pyogranulomatous dermatitis.
Bacteria and Malassezia in these lesions are considered secondary invaders and not causative agents.
Demodex mites can be the primary agents of this disease.
TREATMENT
Initial treatment—gentle clipping and soakings to soften crusts.
Continue one or a combination of the therapies listed below until all lesions have resolved.
Discontinue treatment by tapering medication over a 2- to 3-week period.
Recurrent episodes—once the recurrence rate is determined, an appropriate maintenance protocol can be designed for each individual.
Continual episodes—life-long maintenance treatment necessary.
MEDICATIONS
DRUG(S)
Topical
Shampoo—once or twice weekly with antiseborrheic (sulfur-salicylic acid, benzoyl peroxide, or ethyl lactate).
Cleansing agents—benzoyl peroxide, salicylic acid, chlorhexidine-phytosphingosine.
Wet wipes—Douxo Chlorhexidine pads®, Malaseb® wipes, MalAcetic® wipes, GlycoZoo® wipes.
Antibiotic ointment—mupirocin 2%.
Other topicals—clindamycin or erythromycin solution or ointment.
Combination topicals—benzoyl peroxide-antibiotic gels (e.g., Benzamycin).
Topical retinoids—Tretinoin (Retin-A 0.01% gel).
In severe inflammatory periods, 10–14 days of oral prednisolone (1–2 mg/kg q24h) may help to reduce scar tissue formation.
Systemic
Antibiotics—amoxicillin with clavulanate, cephalosporin, or fluoroquinolone.
Severe cases may warrant treatment with isotretinoin (Accutane) or cyclosporine, modified (Atopica).
Demodicosis—oral ivermectin 400 μg/kg daily until mites are cleared.
CONTRAINDICATIONS/POSSIBLE INTERACTIONS
Benzoyl peroxide and salicylic acids—can be irritating.
Some wipes contain alcohols that can be irritating.
Systemic isotretinoin—use with caution, if the animal will not allow application of topical medications; potential deleterious side effects in human beings (drug interactions and teratogenicity); container should be labeled for animal use only and kept separate from human medications to avoid accidental use; currently difficult to obtain for animal patients.
FOLLOW-UP
Monitor for relapses.
Maintenance cleansing programs can be used to reduce relapses. Affected cats are likely to have variable numbers of comedones life-long, often are just cosmetic and treatment is not necessary.
MISCELLANEOUS
PREGNANCY/FERTILITY/BREEDING
Systemic isotretinoin should not be used on breeding animals.