Peer-reviewed veterinary case report
Identification of Ehrlichia risticii as the causative agent of two equine abortions following natural maternal infection.
- Journal:
- Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc
- Year:
- 1995
- Authors:
- Long, M T et al.
- Affiliation:
- Department of Veterinary Medicine · United States
- Species:
- horse
Plain-English summary
Two pregnant mares, both diagnosed with a disease caused by the bacteria Ehrlichia risticii, experienced abortions after recovering from their illness. The first mare showed signs of illness at about four months into her pregnancy and aborted her fetus at around seven months, while the second mare fell ill a bit later and aborted a few weeks after that. The fetuses were found to have some signs of distress, like staining from meconium (a substance found in the intestines of newborns) and other internal issues. Tests confirmed the presence of Ehrlichia risticii in various tissues of the fetuses, and when the bacteria was introduced to another pony, it developed symptoms like low energy, stopped eating, and mild diarrhea. This research shows that Ehrlichia risticii can cause abortions in horses and should be considered when investigating similar cases.
Abstract
Two pregnant mares diagnosed as having equine monocytic ehrlichiosis based on history, clinical signs, and high serum antibody titers to Ehrlichia risticii aborted subsequent to recovery from illness. Mare 1 and mare 2 experienced clinical illness at 120 and 143 days of gestation and aborted at 203 and 226 days of gestation, respectively. The fetuses were expelled in fresh condition, and both mares retained their placentas upon abortion. Gross findings for the fetuses included meconium staining and petechiation of external surfaces. Internally, there was increased volume of feces within the small and large intestines and liver discoloration with enlargement. Microscopic findings included lymphohistiocytic enterocolitis, hepatitis, and myocarditis. Lymphoid hyperplasia and depletion were present in spleen, thymus, and lymph nodes. Ehrlichia risticii was recovered from bone marrow, spleen, lymph node, colon, and liver of the first fetus and bone marrow and colon of the second fetus. Electron microscopic evaluation of the organism isolated in cell culture revealed morphology consistent with E. risticii. The isolated organism was inoculated into a naive pony, and this pony developed high levels of antibody against E. risticii, became ehrlichemic, and developed clinical signs of depression, anorexia, and mild diarrhea. These findings confirm that E. risticii is an abortifacient under conditions of natural infection and should be considered as a differential diagnosis of equine abortions.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/7619902/