APOC4 and Doyne honeycomb retinal dystrophy: In conclusion, the differential expression of plasma proteins was associated with DHD pathogenesis in calves, and the FN1 and APOC4 might be the potential clinical biomarkers for diagnosis of DHD in calves, and the intestinal immune network of IgA production, caffeine metabolism, purine metabolism, and PI3K signaling pathway are the candidate targets to treat DHD in calves.