Monitoring Foals by Thoracic Ultrasonography, Bacterial Culture, and PCR: Diagnostic of Rhodococcus equi Subclinical Pneumonia in South of Brazil

Pneumonia caused by Rhodococcus equi is an insidious disease of young foals in which clinical signs may not be apparent until pathologic changes are well progressed. Thus, early and accurate diagnosis of foals with R. equi pneumonia is crucial. Thoracic ultrasound screening and polymerase chain reaction (PCR) from fecal and nasal swab samples were performed in 22 foals from 3 to 16 weeks of age from three endemic farms located in the south of Brazil to identify the occurrence of R. equi subclinical disease/pneumonia. The association of thoracic ultrasonography and fecal PCR detection of virulent R. equi provided a possibility of identification of critical points in disease control. Considering that 95.4% of the foals showed evidence of subclinical disease based on pulmonary abscessation or consolidation but none of them developed R. equi pneumonia, antibiotic treatment does not seem necessary in the population studied.