A prospective study evaluating the correlation between local weather conditions, pollen counts and pruritus of dogs with atopic dermatitis

Background: Canine atopic dermatitis (cAD) is a hereditary, generally pruritic and predominantly T-cell-driven inflammatory skin disease, involving an interplay between skin barrier abnormalities, allergen sensitisation and microbial dysbiosis. The individual immunological response is predominantly against environmental allergens, including mite antigens; mould spores; and pollen from grasses, trees and weeds. Airborne pollens show fluctuating patterns during the year. Objective: The aim of this prospective study was to evaluate the influence of local pollen concentrations and weather conditions on the clinical signs of atopic dogs, and to investigate any possible correlations with the results of intradermal testing (IDT). Materials and Methods: Thirty-seven privately owned atopic dogs in Bavaria were surveyed from 1 April to 30 November 2021. Owners were asked to record pruritus using a validated Visual Analog Scale (PVAS) score and the weekly medication of their dog. Furthermore, weather data, including pollen count, rainfall, relative humidity, hours of sunshine and temperature from the dog's location were collected daily. Results: Of the evaluated parameters, only humidity and medication scores correlated positively with the PVAS scores of the atopic dogs. There was no correlation between specific pollen counts and PVAS scores of dogs with positive IDT reactions to that pollen. Conclusion and Clinical Relevance: The outcome of this study highlights the importance of a careful interpretation of positive IDT results in dogs with cAD and questions the validity of airborne pollen trap methodology in representing pollen exposure for dogs at ground level.