+1 Recommend
0 collections
      • Record: found
      • Abstract: not found
      • Article: not found

      The effect of bacterial dose and foal age at challenge on Rhodococcus equi infection

      , , , , ,

      Veterinary Microbiology

      Elsevier BV

      Read this article at

          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.


          While Rhodococcus equi remains the most common cause of subacute or chronic granulomatous bronchopneumonia in foals, development of a relevant model to study R. equi infection has proven difficult. The objective of this study was to identify a challenge dose of R. equi that resulted in slow progressive disease, spontaneous regression of lung lesions and age-dependent susceptibility. Foals less than one-week of age were challenged intratracheally using either 10(6), 10(5), 10(4), 10(3) or 10(2) cfu of R. equi. Two doses (10(3) cfu and 10(5) cfu) were used to challenge 2 and 3-week-old, and 3 and 6-week-old foals, respectively. Physical examination, thoracic ultrasound and blood work were performed. Foals were euthanized at the end of the study or when clinical signs of pneumonia developed. All foals were necropsied and their lung lesions scored. Foals challenged with low concentrations of R. equi developed slow progressive pneumonia and approximately 50% of the foals recovered spontaneously. Likewise, macroscopic (>1cm diameter) pyogranulomatous lesions were only observed when low doses of R. equi were used. Clinical pneumonia was not seen after low dose challenge in the 3-week-old foals or in the 6-week-old foals. This study demonstrates that the use of low doses of R. equi to challenge neonatal foals provides an improved model for studying this disease. Furthermore, susceptibility to R. equi infection was shown to diminish early in the foal's life, as has been reported in the field.

          Related collections

          Author and article information

          Veterinary Microbiology
          Veterinary Microbiology
          Elsevier BV
          December 2013
          December 2013
          : 167
          : 3-4
          : 623-631
          © 2013


          Comment on this article