Systemic Inflammation in Dogs with Atopic Dermatitis Compared to Healthy Dogs and Dogs with Pemphigus Foliaceus: A Study Using a Limited Cytokine Panel.

BACKGROUND:Atopic dermatitis (AD) is a common chronic, pruritic and inflammatory skin disease in both humans and dogs. In people, AD is increasingly recognised as a systemic inflammatory disease in which immune dysregulation drives chronic inflammation extending beyond the skin, particularly in moderate-to-severe disease. Whether a comparable systemic inflammation exists in canine AD, however, remains poorly characterised. HYPOTHESIS/OBJECTIVES:We hypothesised that serum cytokine concentrations would differ between dogs with varying AD severity and healthy controls. This study aimed to identify systemic inflammatory markers correlating with AD severity, by comparing cytokine profiles in dogs with mild AD and moderate-to-severe AD against healthy dogs (negative control) and dogs with active pemphigus foliaceus (PF) lesions (positive control). ANIMALS:Forty client-owned dogs were enrolled, with 10 dogs in each of four groups: healthy controls, mild AD, moderate-to-severe AD and PF. MATERIALS AND METHODS:Serum concentrations of tumour necrosis factor (TNF)-α, TNF-β/lymphotoxin-α, interleukin (IL)-1β, IL-6, IL-12 and IL-1 receptor antagonist (IL-1RA) were measured using standardised immunoassays to evaluate systemic inflammation across groups. RESULTS:Marked interindividual variability was observed across all groups. No statistically significant differences in serum concentrations of any of the six cytokines were detected between the healthy, mild AD, moderate-to-severe AD and PF groups. CONCLUSIONS AND CLINICAL RELEVANCE:In a limited cytokine panel, no evidence of differential systemic inflammation was detected across groups, including dogs with moderate-to-severe AD compared to healthy controls. These findings may reflect true lack of systemic inflammation in dogs or may be attributable to the small sample size, high interindividual variability or the limited scope of the cytokine panel evaluated.