Background: Natural rubber latex (NRL) allergy has become an important occupational health problem in humans, with a higher prevalence in asthmatic individuals. However, the occurrence of NRL sensitisation in horses with severe equine asthma (sEA), a condition comparable to human allergic asthma, is unknown. Method: Specific IgE levels against 10 different Hev b proteins were measured in sera from n = 57 sEA-affected and n = 81 non-affected horses using a microarray platform. Slides were scanned in a GenePix® 4000B with GenePix® Pro 6 software. Multivariant modeling was used to rank the importance of individual allergens. Results: Modelling revealed a high association of Hev b 11, Hev b 6.02 and Hev b 5.0101 allergies in severe equine asthma patients. Given the adjuvant and sensitising effects of latex, these airborne particles could contribute to the increase in both latex sensitisation and asthma through direct and indirect mechanisms. The source of sensitisation to latex is yet to be determined, however the equine environment is ubiquitous with artificial riding surfaces which often contains shredded rubber. Conclusion: This study demonstrated a high prevalence of in vitro NRL allergies within the severe equine asthma population. At present, exposure should be considered a potential risk to the respiratory health of the horse.