Feline acne

FELINE acne is an uncommon disorder of follicular keratinisation and glandular hyperplasia. It is relatively uncommon compared to the dog and unlike dogs and humans, feline acne is not predisposed to adolescence being seen in cats of all ages, breeds and gender.

There are various suggested underlying causes although none of these has been shown to be a definitive cause. They include (Miller, Griffin and Campbell, 2013):

• Poor grooming associated with obesity, mouth and teeth disease Underlying seborrhoeic predisposition
• Abnormal sebum production
• Hair cycle influence
• Stress
• Viruses
• Immunosuppression

There is no evidence of any hormonal influence and the frequency in males and females is the same.

Clinical findings

• Initial and often long-standing lesions are comedones (Figure 1).
• These are often unnoticed or ignored by the owner.
• In approximately half of the cases there may be a deterioration with the development of papules and/or pustules.
• In severe cases there is furunculosis and cellulitis with draining tracts. Bacteria that may be isolated include Pasteurella multocida, beta-haemolytic Streptococci, Staphylococci, Malassezia or a dermatophyte (Miller, Griffin and Campbell, 2013).
• In chronic cases there may be oedema, thickening of the skin and the development of scar tissue.

Differential diagnosis

The differential diagnosis includes:

• Eosinophilic granuloma manifesting as “fat chin” (Figure 2);
• Malassezia (Figure 3);

and less commonly,

• Demodicosis
• Dermatophytosis
• Canine tooth root abscess leading to regional cellulitis Diagnosis
• History and physical examination are usually distinctive.
• Cytology – in many cases this is the most useful initial test and will identify bacterial and yeast involvement.
• Biopsy – this is rarely needed and is usually reserved for more serious cases or in those that do not respond quickly to treatment. Histopathological findings include follicular hyperkeratosis, follicular plugging and dilatation, glandular hyperplasia and in the presence of secondary bacterial infection perifolliculitis, furunculosis and cellulitis (Gross, Ihrke, Walder and Affolter, 2005).

Clinical management

Most cases benefit from topical treatment although many cats suffer relapses and management may need to be intermittent and life-long.

• Gentle clipping in long-haired cats
• Antibacterial shampoos such as ethyl lactate
• Topical 2.5% benzoyl peroxide gels (occasionally irritant)
• Fusidic acid (without steroid) ointment, or mupirocin ointment

In severe secondary infection, systemic treatment may be necessary. This will include systemic antibacterial treatment for 21 to 28 days based on culture and sensitivity testing or itraconazole (Itrafungol, Elanco) in those cases that also have Malassezia infection.

In resistant cases oral isotretinion at a dose of 2mg/kg/day has been advocated (Rosencrantz, 1996).

References and further reading

Gross, T. L., Ihrke, P. J., Walder, E. J. and Affolter, V. K. In: Skin Diseases of the Dog and cat. Clinical and Histopathologic Diagnosis. pp437-440. Blackwell Publishing, 2005.

Miller, W. H., Griffin C. E. and Campbell, K. L. In: Muller and Kirk’s Small Animal Dermatology. pp 640-642. Elsevier, 2013.

Rosencrantz, W.S. (1996) The pathogenesis, diagnosis and management of feline acne. Vet Med 86: 504.