144. Application of Thoracic Ultrasound for Identifying Subclinical Respiratory Disease in Goats Enrolled in a Buck Performance Test

Abstract Respiratory disease is a leading cause of performance loss in livestock, resulting in economic losses for producers. Subclinical disease often goes undetected using traditional clinical scoring methods. The objective of this descriptive study was to assess the feasibility of thoracic ultrasound (TUS) for detecting subclinical respiratory disease in goats enrolled in the Mississippi buck test program. Although TUS has been validated for identifying subclinical respiratory disease in calves, its application in goats has not been established. We hypothesized that thoracic ultrasound would be a useful diagnostic tool to detect subclinical respiratory disease in goats. Goats (n = 30) from 5 different states across the South and Midwest, including OK, IN, WV, AL, and MS enrolled in the 2025 Southeastern buck test, conducted at H. H. Leveck Animal Research Center, hosted by Mississippi State University Extension. At enrollment, each animal underwent a health check and was placed in confinement for two weeks. Thoracic ultrasound examinations were conducted at enrollment and on a weekly basis for the remainder of the 84-day test using a portable ultrasound unit equipped with a linear probe (Ibex Pro NXT, hybrid rectal convex probe, 7.5MHz). Lung lesions were defined as the presence of consolidations greater than or equal to 1 cm, with subclinical disease classified as lesions in the absence of clinical signs such as nasal discharge or coughing. Nasal swabs were collected upon arrival and when animals showed a lung score consistent with subclinical pneumonia. One swab was used to sample both nostrils for bacterial analysis. Animals with respiratory signs were treated with Draxxin (tulathromycin) at a dose of 2.5 mg/kg administered intramuscularly. Of the 30 bucks evaluated, 87% (26/30) had subclinical pneumonia, as determined by ultrasound, during the testing period. At enrollment (D0), 10% (3/30) of the goats showed lung scores consistent with respiratory disease. By D14, the cumulative incidence had reached 77%, and by D42, 87% of the population had been affected (Figure 1). Thoracic ultrasound identified lung consolidations consistent with subclinical pneumonia in animals that were clinically normal at the time of scoring. Overall treatment response to Draxxin was 92%, with improvements evident within 7–14 days post-treatment. TUS proved feasible for detecting subclinical respiratory disease in goats enrolled in the buck test. TUS detected lung consolidations that were not visible through clinical signs, showing its potential as a valuable tool for small ruminant health management. Treatment of subclinical cases resulted in excellent antibiotic effectiveness. Early detection and treatment with this method could reduce disease spread, improve animal welfare, and boost productivity. Overall, these findings provide small ruminant producers with a diagnostic approach similar to those used in cattle, strengthening goat health management nationwide.