Prevalence and characteristics of ocular lesions associated with acaricide usage in cattle on selected farms in Sanga Town Council Kiruhura District,Uganda.

Abstract

Ocular lesions in cattle are an emerging concern in Uganda’s livestock sector, particularly in regions where chemical tick control is heavily practiced. Inappropriate use of acaricides, including over-dilution, excessive application, and the use of non acaricide pesticides, has raised public and animal health concerns. However, empirical data linking these practices to ocular lesions in cattle remain scarce. This cross-sectional study, conducted between March 2025 and May 2025, investigated the prevalence and characteristics of ocular lesions and their association with acaricide usage practices among cattle on selected farms in Sanga Town Council, Kiruhura District, Uganda. A total of 141 cattle farms were randomly selected from the entire Town Council. Data was collected using researcher-administered semi-structured questionnaires, physical examination of cattle to identify ocular lesions, and histopathological analysis of 10 eye samples with gross lesions collected from 10 slaughtered animals. Questionnaire data was analyzed using STATA version 14.2, with descriptive and inferential statistics performed. The overall farm-level prevalence of ocular lesions was 77.3% (109/141, CI; 69.6%-83.5%), while the herd-level prevalence was 9.5% (753/7904). The majority of farms used amidine-based acaricides (83.7%), and hand spraying was the predominant application method (92.9%). Although no statistically significant association was found between ocular lesions and specific acaricide types (p = 0.900), a strong association was observed between the occurrence of ocular lesions and the use of non-acaricide pesticides (p = 0.002). The gross lesions observed included corneal opacity, conjunctival redness, and ulceration. Histopathological findings across all 10 samples consistently showed corneal epithelial hyperplasia and degeneration, with some samples showing stromal vascularization, and inflammatory cell infiltration in the conjunctiva and lens degeneration. The findings of this study suggest a high burden of ocular lesions among cattle in Sanga Town Council, likely influenced by irrational chemical use. The findings underscore the need for improved farmer education, stricter regulatory oversight, and development of safer acaricide application protocols to protect cattle health and welfare. Further longitudinal or experimental studies are needed to establish a clearer causal relationship between specific acaricide exposure and the development of ocular lesions in cattle. Keywords: Cattle, Ocular Lesions, Acaricides, Non-acaricide Pesticides, Animal Health.