 Enzyme-linked immunosorbent assays (ELISAs) have been used as a diagnostic tool to quantify the impact of gastrointestinal nematodes in dairy cattle by measuring antibodies in milk.Higher levels of antibodies measured by ELISA methods, referred to as optical density ratios (ODRs), are associated with decreased milk production in dairy cattle.Similar results have been established in the dairy industry between increased ODR and negative effects on health, body weight and reproductive measures
Blood pepsinogen concentration, which increases with abomasal mucosa injury has also been used to diagnose ostertagiosis.