First case of equine nocardioform placentitis caused by Crossiella equi in Europe.

The research article is about the first recorded case in Europe of a horse suffering from nocardioform placentitis (a specific type of bacterial infection that affects pregnant mares) that was caused by the bacterium Crossiella equi.

Background and Case Presentation

• Nocardioform placentitis is a unique type of bacterial infection that affects the placenta of pregnant horses, first observed in the U.S. in the late 80s. It’s caused by a variety of Gram-positive bacteria which are filamentous and branching, like the Nocardia species, Rhodococcus rubropertinctus, and Amycolatopsis species.
• This case report presents the infection caused by Crossiella equi in a mare located in northern Italy. The mare, aside from having chronic laminitis, had had normal pregnancies prior to the infection.
• Before the abortion, the mare had a hemorrhagic vaginal discharge but without any other clinical symptoms. Despite the placenta appearing separated on an ultrasound, no treatment was administered.

Postmortem Examination and Laboratory Tests

• After the abortion, the fetus and fetal membranes were examined. The fetus was found to be normally formed but significantly underweight. The external mucosae were pale, and visceral organs presented considerable congestion.
• A solitary, well-defined area on the placenta was found covered with a necrotic, mucopurulent exudate. Tissue samples from both the fetus’ organs and the placenta were procured for bacteriological, virological, and mycological cultures, along with histological analysis.
• Gram-stain tests from the placental exudate revealed numerous filamentous, Gram-positive bacteria. Tissue sections of the fetal organs showed only mild congestion of the liver and spleen, interstitial edema of the myocardium (heart muscle), and necrosis (death of cells) of the kidney’s tubular epithelium.
• The allantochorion (part of the placenta) showed significant inflammatory changes, including areas of mucopurulent and necrotizing placentitis. Sections stained with Brown and Brenn’s method revealed the filamentous, Gram-positive bacteria. However, Grocott and Ziehl-Neelsen stains administered on the placenta were negative.

Conclusion

• This research is the first reported incidence in Europe of equine nocardioform placentitis associated explicitly with Crossiella equi, thus expanding our understanding of the geographical and species spread of this condition.