Presumed immune-mediated hemolytic anemia in two foals with Rhodococcus equi infection

Authors

  • Imogen C. Johns BVSc, DACVIM,

    1. George D. Widener Hospital for Large Animals, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
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  • Anne Desrochers DVM, DACVIM,

    1. George D. Widener Hospital for Large Animals, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
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  • Kathryn L. Wotman DVM, DACVIM,

    1. George D. Widener Hospital for Large Animals, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
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  • Raymond W. Sweeney VMD, DACVIM

    1. George D. Widener Hospital for Large Animals, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
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  • Authors declare no conflict of interest.

  • Present address: Dr. Imogen C. Johns, Department of Veterinary Clinical Science, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts, UK AL9 7TA.

  • Present address: Dr. Anne Desrochers, Marion duPont Scott Equine Med Ctr, 17690 Old Waterford Rd, PO Box 1938, Leesburg, VA 20177, USA.

Address correspondence and reprint requests to
Imogen C. Johns, Department of Veterinary Clinical Science, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts, UK AL9 7TA.
Email: ijohns@rvc.ac.uk

Abstract

Objective – To describe the clinical presentation, case management, and outcome in 2 foals with Rhodococcus equi infection associated with presumptive severe immune-mediated hemolytic anemia.

Series Summary – Two foals diagnosed with R. equi pneumonia on the basis of tracheal wash cultures, thoracic radiographs, and thoracic ultrasonography were concurrently diagnosed with hemolytic anemia. Both foals required whole blood transfusions, and were treated with the antimicrobial combination of rifampin and a macrolide (eg, clarithromycin, erythromycin, or azithromycin). Dexamethasone was used to prevent further hemolysis in both foals, and to treat acute lung injury/acute respiratory distress syndrome in 1 of the foals. Both foals survived, and required prolonged antimicrobial therapy.

New or Unique Information Provided – Although extra-pulmonary disorders are commonly diagnosed in foals infected with R. equi, hemolytic anemia is rarely described. Dexamethasone is considered the treatment of choice for immune-mediated hemolytic anemia, but may be contra-indicated in foals with severe bacterial infections. In these foals, a relatively low dose and short duration of dexamethasone was utilized in an attempt to minimize immune suppression, although early discontinuation in 1 foal precipitated a second hemolytic crisis.

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