Environmental and Management Factors Associated withCutaneous Lupus Erythematosus Occurrence in Horses of AjmerDistrict, Rajasthan, India

Abstract

Cutaneous Lupus Erythematosus (CLE) is a photosensitive autoimmune dermatological
disorder influenced by interactions between immune dysregulation, genetic susceptibility, and
environmental triggers. Although CLE has been described in horses, population-level
information regarding climatic, environmental, and management factors associated with
disease occurrence remains limited. The present study was conducted to evaluate the
association of climatic conditions, environmental exposure, and management practices with
CLE occurrence among horses in Ajmer district, Rajasthan, India. A two-year cross-sectional
epidemiological study was conducted during 2024–2025 involving 360 horses examined from
farms, stables, equine establishments, and rural locations. Clinical and dermatological
examinations were performed, and suspected cases were confirmed through histopathological
evaluation. Climatic variables including daily maximum temperature and relative humidity,
along with environmental and management factors such as sunlight exposure, housing system,
shade availability, outdoor exposure, and protective management practices were assessed.
Among the examined horses, 27 were classified as CLE-positive, resulting in an overall
prevalence of 7.5%. Higher CLE prevalence was observed among horses exposed to prolonged
sunlight (10.0%), high maximum temperature conditions (>40°C; 9.3%), and low relative
humidity (<30%; 9.3%). Similarly, open housing systems, inadequate shade availability,
continuous outdoor exposure, and poor protective management were associated with increased
CLE occurrence. One-way ANOVA revealed significant effects of sunlight exposure, housing
system, shade availability, outdoor exposure, management practices, and temperature,
whereas relative humidity showed a marginal association with CLE occurrence. The findings
indicate that climatic and environmental conditions may act as important modifiers of equine
CLE expression. Improved environmental management, including shade provision, controlled
outdoor exposure, and reduction of excessive solar stress, may help reduce the risk and severity
of CLE in horses maintained under semi-arid climatic conditions.