Dandruff in cats: seborrhoeic dermatitis in cats

Seborrhoeic dermatitis is an inflammatory keratinisation disorder of the skin, usually of a chronic and/or recurrent nature. This type of dermatitis is characterised by oily seborrhoea and adhesions of a yellowish-brown fatty material with a greasy appearance.¹

It usually courses with pruritus, folliculitis, pyoderma, inflammation and dandruff in cats, and is normally found on the shoulders, skin folds and face, especially in areas susceptible to chaffing, such as the lips, ears and periocular region.²

Seborrhoeic dermatitis: aetiology

The pathophysiology of seborrhoeic dermatitis has not been fully clarified. Primary seborrhoeic dermatitis, for example, has a hereditary character and breed predisposition, having a higher prevalence in Persian and Devon Rex cats, as indicated in a study by Bond.³

However, most cases involve secondary seborrhoeic dermatitis due to an underlying disease, such as a nutritional or metabolic disorder, neoplasm, dermatophytosis or an allergy that causes excessive scaling of the skin.⁴

Several studies, including one carried out by Crosaz O⁵ in cats and another carried out by Yurayart C⁶ in dogs, have identified a link between seborrhoeic dermatitis and yeast of the genus Malassezia, in particular M. pachydermatis overgrowth.

However, everything seems to indicate that the presence of Malassezia alone is not enough to provoke the disorder. As such, seborrhoeic dermatitis in cats is probably a multifactorial condition involving both genetic predisposition and host interactions with environmental factors, including nutrition, immune system status, sebaceous gland activity and epidermal barrier function, as suggested by Older C.E.⁷ in a study that analysed factors influencing feline skin microbiota.

Differential diagnosis

There is a long list of possible disorders if the patient has an exfoliative or seborrhoeic-keratosis dermatological disorder, including sebaceous adenitis, primary idiopathic seborrhoea, feline acne, Persian “dirty face” disease, tail gland hyperplasia, hyperthyroidism, epitheliotropic lymphoma, exfoliative dermatitis associated with a thymoma, and ichthyosis.⁸

Seborrhoeic dermatitis: diagnosis

In many cases, a complete blood count, blood chemistry and electrolyte analyses are required to investigate any underlying subclinical conditions or imbalances.

Histopathology will reveal abnormal keratinisation of the epidermis and hair follicles with the presence of orthokeratotic and parakeratotic hyperkeratosis, follicular hyperkeratosis, dyskeratosis and superficial perivascular dermatitis.⁹

Seborrhoeic dermatitis in cats: treatment

In the case of primary or idiopathic seborrhoea where the underlying cause cannot be determined, treatment should focus on eliminating scabs and dandruff from cats, as well as reducing lipids, pruritus and inflammation.

• Vitamin A can prove helpful in this regard.
• Retinoids, such as isotretinoin, which have an impact on keratinocyte differentiation, may be effective.¹⁰
• A study by Pulido-Villamarin¹¹ also found that antifungal agents, such as itraconazole and ketoconazole, help limit the growth of Malassezia.
• Immunomodulators and corticosteroids, e.g., prednisone, are also known to reduce the production and action of proinflammatory cytokines from keratinocytes and neutrophils, thus mitigating the onset and spread of skin inflammation.
• The use of a salicylic acid and sulphur containing shampoo can have positive results in mild cases. It should be noted that coal tar shampoos are recommended for severe cases in dogs but are contraindicated in cats.¹² These antiseborrhoeic products reduce epidermal division and normalise keratinocyte renewal rates. 

Cases of secondary seborrhoeic dermatitis have a good prognosis when the underlying disease can be resolved, but primary keratinisation disorders require lifelong treatment.⁹

References

1. Rejas, J.; Goicoa, A.; Payo, P. & Balazs, V. (2011) Manual de dermatología de animales de compañía. In: Universidad de León.

2. Saló, E. & Luera M. (1989) Protocolo diagnóstico y revisión de las Dermatosis Faciales más frecuentes en el perro y en el gato. Revista Avepa; 9 (2): 13-78.

3. Bond, R. et al. (2008) Carriage of Malassezia spp. yeasts in Cornish Rex, Devon Rex and Domestic short-haired cats: a cross-sectional survey. Vet Dermatol; 19(5): 299-304.

4. Laverde, J. (2018) Actualización de las principales dermatopatías en perros y gatos, diagnóstico y tratamiento. Universidad de Ciencias Aplicadas y Ambientales. (Veterinary surgeon dissertation)

5. Crosaz, O. et al. (2013) Generalized dermatitis associated with Malassezia overgrowth in cats: A report of six cases in France. Medical mycology case reports; 2: 59–62.

6. Yurayart, C. et al. (2011) Comparative analysis of the frequency, distribution and population sizes of yeasts associated with canine seborrheic dermatitis and healthy skin. Vet Microbiol; 148(2-4): 356-362.

7. Older, C. E. et al.  (2019) The feline cutaneous and oral microbiota are influenced by breed and environment. PloSone; 14(7): e0220463.

8. Lorente Mendez C. Aproximación al diagnóstico de enfermedades dermatológicas en la especie felina. Centro Veterinario; 20-29.

9. Bourguignon, E.; Diegues, L.; Sell, T. & Silva, E. (2013) Dermatology in dogs and cats. Insights from Veterinary Medicine. In: IntechOpen.

10. De León, N. (2009) Uso de retinoides sintéticos en dermatología veterinaria. Universidad de la República. (Veterinary sciences PhD thesis)

11. Pulido-Villamarín, A. et al. (2011) Análisis retrospectivo (2009-2010) de las alteraciones dermatológicas, óticas y oftalmológicas con diagnóstico clínico presuntivo de micosis en caninos y felinos. Universitas Scientiarum; 16 (3): 272-281.

12. Rosenkrantz, W. (2006) Practical applications of topical therapy for allergic, infectious, and seborrheic disorders. Clin Tech Small Anim Pract; 21(3): 106-116.