Zonulin, almost well recognized protein, not solely influence the integrity of intercellular connections int the gut, but also could be capable of modulating lung permeability. It is best known as biomarker/regulator of gastrointestinal tight gap junctions. On the other hand cumulative evidence is growing regarding gut-lung axis also in cattle. The purpose of this present cohort study was to establish the relationship between circulating zonulin levels and severity of respiratory problems among disease calves upon referral at a milk-fed veal facility, 20 calves with a diagnosis of bovine respiratory disease were scored for calf respiratory scoring chart previously identified and well designed. Scores >5 were identified as active disease (severe pneumonia), whereas scores <5 were denoted as exposure (without severe pneumonia). Commercially available specific Bovine Zonulin ELISA test kits were used. Ethical guidelines were strictly followed up with written owner consent was available for all calves enrolled. The mean zonulin levels (ng/mL) healthy calves, calves without severe pneumonia (Score <5) and calves with pneumonia (Score >5) were detected as 21.03 ± 10.57, 39.53 ± 11.90 and 64.69 ± 17.98, respectively. There was statistically significant alterations in calves with severe pneumonia in contrast to healthy calves (p<0.05). As preliminary findings of the present reseacrh zonulin is not solely limited to expression of intestinal inflammation and thus circulating zonulin levels should be interpreted in possible lung injury (and or lung permeability) in correlation with disease activity on field conditions for prognosis and available treatment practices.