High prevalence of Chorioptes bovis: an important factor in chronic progressive lymphedema in Belgian draft horses

A cross-sectional study was conducted to estimate the prevalence of chorioptic mange affecting the distal legs of horses in Belgium, focusing on the association between mange and chronic progressive lymphedema (CPL) in Belgian draft horses. Clinical examinations and skin scrapings were performed on the distal legs of 156 Belgian draft horses and 142 Belgian warmblood horses. In the Belgian draft horse breed, 144 (92.31%) horses were infested with Chorioptes bovis mites, and 126 (80.77%) displayed clinical signs of CPL. CPL prevalence in draft horses aged < 1 year was 17.86%, while mites were detected in 85.71% of this age group, with infestations observed as early as 6 days of age. In a subset of horses aged ≥ 1 year, CPL and mange prevalence amounted to 94.53% and 93.75%, respectively. In contrast, no mites or CPL were detected in the Belgian warmblood horses examined. Statistical analysis revealed a strong association between C. bovis and CPL (prevalence odds ratio: 7.37; p = 0.002). The prevalence of CPL was approximately twice as high in horses with mites compared to non-infested horses (prevalence ratio: 2.02). Furthermore, the prevalence risk difference of 42.36%, indicates a substantial absolute increase in CPL prevalence among infested horses. This study demonstrates the high prevalence of C. bovis and its breed-specific predilection in Belgian draft horses. The strong association between mange and CPL highlights the potential role of C. bovis as a contributing factor in CPL pathogenesis.