Nocardioform placentitis in a sample population of mares foaling in southeastern Pennsylvania and northeastern Maryland in 2020.

The research article focuses on investigating a series of cases on Nocardioform placentitis (NP), a pregnancy-affecting disease among horses, in southeastern Pennsylvania and northeastern Maryland in 2020, which coincided with an outbreak of the same disease in Kentucky during the same period.

Introduction and Context

• Nocardioform placentitis (NP) in horses is a bacterial infection that affects the placenta and can result in mid to late pregnancy loss in mares, or female horses.
• Previously, outbreaks and cases of this disease had been largely reported in Kentucky, with a few isolated instances reported globally. This study, however, analyzed the incidence of NP in populous out-of-Kentucky regions, namely southeastern Pennsylvania and northeastern Maryland in 2020.
• The study was triggered by a coincidence with an outbreak of NP in Kentucky during the same period.

Sampling and Results

• The population sample for this study was composed of 299 mares that were foaling in these regions during 2020.
• Based on aerobic culture and PCR testing, nocardioform organisms or DNA were found in 6.3% of placental samples from farms that had reported both normal and abnormal foalings.
• Moreover, the study found that in instances where visible lesions of the chorion (outermost layer of the placenta) were present, 41% of cases tested positive for NP.
• In total, 16 mares that had never been to Kentucky for breeding or any part of their gestation, were confirmed to have NP.

Comparison and Analysis

• The study examined the characteristics of mares found to have NP, including their age, gestation length, and any complications they may have had during gestation.
• A key finding from this study is that Standardbred mares, who were bred using artificial insemination, were less likely to be affected by NP compared to Thoroughbred mares, who were bred using natural cover.
• Also, mares that were affected by NP were found to have prolonged Stage III labor (delivering the placenta) compared to normal mares.

Conclusion

• This study highlights that regional increases in NP can occur outside of the previously assumed ‘hotspot’ of Kentucky.
• This suggests that there may be a synchronous occurrence of outbreaks in multiple regions, leading to an increased understanding of the disease’s geographical distribution.