Acne is a skin disease of cats that primarily affects the chin.  Most owners present their cats to the veterinarian for evaluation of a “dirty chin.”

Prevalence

Acne is a fairly common skin disorder of the cat.  It is not confined to a particular age grouping and may occur in a cat of any age.

Clinical Signs

Acne lesions are most often on the chin and lower lip.  Sometimes, the upper lip may also be involved.  Without close examination, the cat may appear to have a dirty chin.  It is more difficult to see the lesions if the cat has a dark haircoat.

The typical lesion is a comedone (“blackhead”) and, occasionally, superficial pimples are seen.  With progressive involvement, the hair follicle may become plugged with secretions and rupture into deep layers of the skin. If this happens, the chin becomes swollen and very angry in appearance.  The cat becomes sensitive and resists touching and treatment.

In severe, long-standing cases, scarring and cysts may be observed.

Causes/Transmission

The cause of feline acne remains unknown; realistically, it is likely that there are multiple causes.   Some of the possible causes include:

1. Poor grooming habits.
2. Abnormal production or composition of sebum, which is a waxy or oily substance produced by glands in the skin.
3. Clogging of the hair follicles when hair is not properly shed.
4. Defects in keratin production.  Keratin is a protein which gives the skin it’s protective coating. 

In humans, acne is related to hormone levels and the presence of bacteria in the skin.  A clear association between hormones, skin bacteria and development of acne has not been demonstrated in the cat.

Diagnosis

Acne is most often diagnosed based on its characteristic appearance, sometimes called a "dirty chin." 

In order to eliminate other possible causes of an infection on the chin, several diagnostic tests may be performed.  In most cases these are not necessary but, when indicated, typically involve scraping of the skin to look for mites and a culture for bacteria and/or fungi.

Treatment

Topical treatment is usually adequate for most cases of acne; severe cases may require systemic (oral) therapy.

Treatment begins with clipping of the chin.  This permits deep cleaning of plugged follicles and application of medication to the lesions.  Because the cat's chin may be rather sensitive, sedation may be required to accomplish adequate clipping and initial cleaning. 

Treatment is continued at home.  The pores of the skin are opened with the application of heat.  A wash cloth is placed under hot water, and the excess water squeezed out.  This hot pack is placed on the chin for 2-4 minutes.  When it is removed, topical medication is applied.  There are several effective medications available, and their choice is partially determined by the presence of absence of infection.

If infection is present, antibiotics or antifungal drugs may be given orally. 

Topical and oral Retin-A (vitamin A) have been tried, but the response is variable and the medication can be very irritating to the skin.

Prognosis

Acne will recur in many cats.  At the first sign of return, begin hot packing the chin and applying the topical medication.  If this does not control the problem, you cat needs to be re