Feline Atopic Dermatitis

Therapeutic Potential of Vitamin C as an Adjunct Therapy

Abstract

Background: Feline atopic dermatitis (AD), also known as non-flea, non-food hypersensitivity dermatitis, is a chronic pruritic skin condition associated with environmental allergens such as dust mites and pollens. Although the age of onset is variable, it generally occurs before 5 years of age. Similar to dogs, pruritus is a key feature of atopic dermatitis in cats, although the distribution of pruritus and lesions is often more variable. The initial workup should include a thorough history, complete dermatologic and physical examination, and routine tests such as flea combing, skin scrapings, and fungal cultures. A diagnosis of feline AD is established once other differential diagnoses have been excluded. The feline dermatitis extent and severity index (FEDESI) and the scoring feline allergic dermatitis (SCORFAD) are commonly used in the evaluation the severity of feline AD. Treatment of feline AD typically involves a combination of anti-inflammatory medications and supportive care to control pruritus and inflammation. Long-term management should be supported by identifying trigger factors and implementing environmental control measures. This study investigated the potential benefits of vitamin C as an adjunctive treatment for feline AD, utilizing the pruritus visual analog scale (pVAS) and the FEDESI as assessment tools. 

Materials, Methods & Results: Twenty cats with dermatological symptoms, free from infectious, parasitic, or fungal diseases, were included. After hematological and diagnostic evaluations, they were divided into 2 groups: Group 1 received methylprednisolone alone, while Group 2 received methylprednisolone combined with vitamin C (25-75 mg/kg) for 14 days. Clinical assessments, pVAS, FEDESI scores, and eosinophil counts were recorded on days 0, 7, and 14. Both groups showed clinical improvement, with reductions in pruritus and skin lesions. However, Group 2 exhibited a more rapid decrease in pVAS and FEDESI scores by day 7. Eosinophil counts also dropped more significantly in the Group 2. By day 14, clinical outcomes were similar between groups, and statistical differences were no longer significant. 

Discussion: Feline AD is a pruritic disease in which affected cats exhibit a hypersensitivity reaction to inhaled or contacted environmental allergens. Skin lesions may be seasonal or non-seasonal. In recurrent cases, otitis externa, miliary dermatitis, pruritis in the head and neck region, and eosinophilic granuloma complex lesions may be associated with atopy. The primary symptom is pruritus, and depending on the severity of pruritus, erosion, excoriations and alopecia may be observed in the lesions. In this study, it was observed that the clinical findings were compatible with the literature data. The primary goal of treatment is to reduce pruritus and inflammation to levels below the threshold for clinical manifestation. To achieve this, a classical multimodal approach is typically employed, incorporating both anti-inflammatory and immunosuppressive agents. Although classical treatment yields highly effective results, vitamin C may be considered as an adjunct therapy in the management of feline AD due to its roles in skin barrier support and antioxidant activity. The findings suggest that vitamin C may contribute to faster short-term relief of clinical signs in feline AD, possibly through its antioxidant, anti-inflammatory, and immunomodulatory properties. While the long-term efficacy remains uncertain, early results indicate that vitamin C can support initial treatment response when used alongside corticosteroids. In conclusion, parenteral vitamin C may serve as a supportive therapy in feline AD, helping to accelerate early clinical improvement. Further large-scale and long-term studies are necessary to confirm its role in routine treatment protocols.

Keywords: atopic dermatitis, feline, vitamin C.