Serum total protein concentration as a risk factor for pneumonia in calves

Background: Bovine respiratory disease complex (BRD), which described as pneumonia caused by one or more infectious agents (various viruses and bacteria, either alone or in combination, as well as by various precipitating factors) and associated with inflammation, consolidation, fibrosis, and lung abscesses. Fibrinous pneumonia is the most common form of acute pneumonia in weaned calves. Determining the form of pneumonia (fibrinous or caseonecrotic) and its differential diagnosis is challenging. This study was carried out to determine the association between serum total protein (TP) concentration and the risk of pneumonia in calves. Methods: This prospective cohort study was conducted on one farm in the Alborz province, Iran, from August to October ۲۰۲۵. The animal material for this study comprised a total of ۱۸۳ Holstein calves under the age of ۳ days. Blood samples were taken from the jugular vein of all calves included in the study using anticoagulant-free tubes so that their serum TP could be analyzed. Serum TP concentration was measured using a refractometer and spectrophotometry. Each calf was observed daily for clinical signs of pneumonia, which include fever, respiratory effort, nasal discharge, cough, and auscultation. The onset of pneumonia was recorded as an event for survival analysis. The Cox proportional hazards regression model was used, in which serum TP concentration was considered as the main explanatory variable. Hazard ratios (HR) and ۹۵% confidence intervals (CI) were calculated. P value less than ۰.۰۵ was considered statistically significant. Results: This study demonstrated a statistically significant association between serum TP concentration and the incidence of pneumonia in calves. The results showed that each ۱ g/dL increase in TP was associated with a ۳۹% increase in the relative risk of developing pneumonia (HR = ۱.۳۸۹, ۹۵% CI: ۱.۰۰۲-۱.۹۲۶, P = ۰.۰۴۹). Conclusion: According to the findings, this study suggests that higher TP levels may be a risk factor for respiratory disease and potentially supports the hypothesis that elevated TP could reflect underlying issues such as dehydration or subclinical inflammation.

کلیدواژه ها:

Calf ، Pneumonia ، STP ، Cox Model ، Hazard Analysis