Acne in cats

Feline acne is a relatively common skin disease in cats, often seen from 12 weeks of age onward. It is sometimes the result of the inability of a cat to clean its chin, but also may be caused by hormonal changes and secondary bacterial folliculitis, as is witnessed in pubertal humans. 

Symptoms

Dirt accumulates on the cat's chin and mixes with normal skin secretions. The hair follicles become plugged, forming 'blackheads' (comedones). Blackheads may become infected, causing small pustules and sores. 

The problem often recurs in susceptible cats and seems related to the hair-growth. There also appears to be a hormonal basis to this disease as it is most common as cats approach puberty (around 6 months of age).

Causes

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The exact cause of feline acne isn't known. There are several possible causes however including 

• Stress

• Hormonal changes, such as onset of puberty

• Food allergies

• Genetic predisposition

• Plastic food bowls is commonly discouraged, especially in cats with feline acne. This is because they are porous and trap bacteria, which is then transferred to the cat's chin. It has also been suggested that an allergic reaction to the plastic food bowl is a cause.

• Poor grooming habits

• Over-active sebaceous glands

The primary change in feline acne is presumed to be an alteration in normal keratinisation in the hair follicle. Initially, keratinous material accumulates in the lower follicular infundibulum resulting in comedo (blackhead) formation. As keratinous material accumulates, it squirts out the follicular ostia, resulting in follicular casts. One theory proposes that affected cats may have larger sebaceous  glands in the chin resulting in excessive or abnormal sebum production. In humans, linoleic acid concentration is lower in the sebum of people with acne and anecdotal reports exist of responses to n-6 fatty acid supplementation in cats with feline acne.

Other factors less likely to be playing an important role include the proposal that affected cats may be grooming inefficiently, permitting surface lipids to accumulate on the skin. It has also been proposed that the cyclic nature of feline acne may be associated with the hair growth cycle. Acne may begin in inactive telogen hair follicles that cannot extrude the keratin out of the follicular ostia. Other host factors such as immunologic status and stress may play a role in the development of feline acne. Occasionally, feline acne has been observed in cats infected with FIV and FeLV viruses, but most patients with acne are negative on viral screening and these viruses are unlikely to be playing any role in the underlying pathogenesis.

Multiple cases of feline acne have been observed in catteries and multi-cat households and an infectious aetiology has been incriminated but never confirmed. In some of these cases, an upper respiratory virus has been a concurrent problem and immunosuppression, direct viral influence and stress have been proposed as contributing factors. In one recent study,  seven of 22 cats with feline acne demonstrated concurrent clinical signs consistent with URTI. While no evidence of FHV-1 was found histopathologically or immunohistochemically in any cat, in one affected cat from a household with five cats simultaneously having feline acne, feline caliciviral ( FCV) antigen was detected in the biopsy of the chin by immunohistochemistry. Chin samples from all other affected cats, as well as the five healthy control cats were negative for FCV. This suggests that FHV and FCV are probably not important in cats with chronic acne.

More advanced cases of feline acne with secondary folliculitis and furunculosis are often complicated with secondary bacterial infection but bacterial infection is not causal. Three types of bacteria have been previously reported to be involved in feline acne: Pasteurella multocida, beta-haemolytic streptococci, and coagulase-positive Staphylococci. Yeast, such as Malassezia and Candida organisms, are occasionally isolated.

There is no evidence to support that androgenic hormones play a role in feline acne.

Treatment

Treatment of feline acne depends on the severity of the condition. Removing excess sebum is the aim. Some treatments include:  

• Topical cleaning with an antibiotic soap, hydrogen peroxide, iodine (Betadine) or Epsom salts. 

• Topical Vitamin A.

• Topical retinoids such as 0.05% Isotretinoin ointment q 24hrs for 4 weeks and then q 48hrs to twice a week.

• In more severe cases, cleansing the skin with an ointment or gel containing benzoyl peroxide (such as OxyDex) or chlorhexidine may be of use.

• Topical glucocorticoids to reduce inflammation, such as 0.1% mometasone q 24hrs for 10 days, then q48hrs to twice a week

• Fatty acid supplementation, such as evening primrose oil 1g/5kg bodyweight daily.

• Broad-spectrum antibiotics such as:

• Systemic antifungals such as