Environmental risk factors for UV-induced cutaneous neoplasia in horses: A GIS approach.

Objective:Ultraviolet light (UV) is a risk factor for the development of cutaneous neoplasia in many mammalian species. This study evaluated UV exposure as a risk factor of concern for the development of cutaneous neoplasia in equine species due to the significant UV exposure that may accrue over their lifetimes. Animals and samples:Neoplastic biopsy specimens from 3272 horses that were submitted over a 10-year period to the Colorado State University Diagnostic Medicine Center and to the University of Saskatchewan Western College of Veterinary Medicine and Prairie Diagnostic Services were evaluated. Procedure:This retrospective study assessed the spatial relationships between altitude, latitude, longitude, and UV maximum value and the probability of UV-induced cutaneous neoplasia. Results:Cases from areas at high altitude proved to have a higher prevalence of UV-induced cutaneous neoplasia than those from areas at lower elevations. A multivariable regression analysis demonstrated that altitude was the only factor significantly and positively associated with the diagnosis of UV-induced neoplasia. Conclusion and clinical relevance:Evidence of cutaneous neoplasia in horses and environmental factors that influence the degree of UV exposure in a geographic location may aid in diagnosis and suggest preventive measures from UV overexposure.