Fig 2. Comparison of induction and regression of ultrasonographic lesions in foals from vaccinated or unvaccinated mares following R. equi challenge.

A: Kaplan-Meier survival plot comparing duration of detectable ultrasonographic lesions as evidence of pulmonary abscessation. Duration of pulmonary lesions identified by ultrasound was significantly (P = 0.008; Log-rank test) shorter for foals of vaccinated mares (solid line) versus those of foals from control mares (hatched line). B: Cumulative sum of maximum diameters of thoracic ultrasonography lesions (N = 7 Controls, 12 Vaccinated). The sums of the cumulative maximum diameters were significantly (P = 0.007; Wilcoxon rank-sum test) lower for foals from vaccinated mares (n = 12) than for unvaccinated control mares (n = 7). Open circles indicate foals diagnosed with pneumonia, filled circles indicate foals that did not develop pneumonia. Symbols with outer gray rings indicate the unvaccinated foal that did not get pneumonia and the vaccinated foal that did develop pneumonia.