Clinical, ultrasonographic, and post-mortem diagnosis of respiratory disease in lambs: hematological and biochemical characterization by severity grade.

Introduction: Respiratory diseases are a major health concern in intensive lamb production, leading to significant economic losses and compromised animal welfare. This study aimed to characterize the hematological and biochemical profiles of lambs affected by ovine respiratory complex according to disease severity assessed by clinical, ultrasonographic, and post-mortem scoring systems. Methods: 89 Lacaune lambs from a single farm were evaluated using a clinical respiratory score, lung ultrasound examination, and macroscopic post-mortem lung assessment, with severity classified into four categories, scores 0 to 3. Blood samples were collected for complete blood count and serum biochemistry analysis. Statistical comparisons were performed using one-way ANOVA and Tukey's Results: Diseased lambs showed significant increases in WBC counts and NEU percentages, with concurrent lymphocytopenia and eosinophilia. RBC parameters varied with disease stage, showing anemia in moderate cases and compensatory increases in severe chronic cases. Biochemically affected lambs exhibited hypoglycemia, decreased ALP activity, hypoalbuminemia, hyperglobulinemia, and hypophosphatemia. Ultrasonographic scores demonstrated greater concordance with post-mortem findings and blood profile alterations compared to clinical scores. Discussion: These results indicate that combining lung ultrasound with hematological and biochemical analysis provide a more efficient evaluation of respiratory disease severity in lambs than a clinical evaluation.