Theriogenology2021; 171; 155-161; doi: 10.1016/j.theriogenology.2021.05.023

Clinical, pathologic, and epidemiologic features of nocardioform placentitis in the mare.

Abstract: Placentitis is the leading cause of infectious abortion in the horse and contributes to roughly 19% of all abortions in the United States. A type of placental infection, nocardioform placentitis (NP) is associated with gram-positive branching actinomycetes localized within the ventral body of the feto-maternal interface to create a lymphoplasmacytic mucoid lesion. While the etiology of this disease is poorly described, this placental infection continues to cause episodic abortions in addition to weak and/or growth retarded neonates. The goal of the present study was to perform a comprehensive analysis of pregnancies associated with a nocardioform-affected placenta and make inferences into the epidemiology of this elusive disease. To do so, 264 mares were enrolled in the study, with 145 as having suspected disease (n = 145; NP) either based on pregnancy-related complications or postpartum placental evaluation, while an additional 119 were enrolled as healthy pregnancies (n = 119; CON). Following diagnosis as either NP or CON based on gross and histopathology at the University of Kentucky Veterinary Diagnostic Laboratory, information was gathered on the mares and neonates for comparisons between diseased and healthy pregnancies. Clinically, a significant portion of diseased mares had clinical indications of NP, including premature mammary gland development, thickening of the placenta noted on transrectal ultrasonography, and separation between the chorioallantois and endometrium noted on abdominal ultrasonography, while vulvar discharge was not commonly noted. Additionally, NP was correlated with increased mare age, decreased gestational length, and decreased neonatal weight, although neonatal IgG and WBC were comparable to CON. Incidence of NP was not correlated with last breeding date, pre- and post-breeding therapeutics, parity, prophylactic medications, or housing. Additionally, NP did not affect postpartum fertility. While NP was associated with a poor neonatal outcome (abortion and/or growth retarded neonate), this did not appear to be influenced by the bacteria isolated (Amycolatopsis spp. vs. Crossiella equi), and mares diagnosed with NP do not appear to be infectious to other pregnant mares nor have repetitive years of the disease. Interestingly, lesion size was positively correlated with last breeding date, as mares bred later in the breeding season correlating with a larger placental lesion. In conclusion, while the etiology of NP continues to elude researchers, the epidemiology of this disease has gained clarity, providing inferences into the management of suspect mares.
Publication Date: 2021-05-25 PubMed ID: 34058508DOI: 10.1016/j.theriogenology.2021.05.023Google Scholar: Lookup
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  • Journal Article

Summary

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This research comprehensively analyzes pregnancies associated with a placental infection called nocardioform placentitis in horses, gathering data from horses diagnosed with the disease and healthy horses to make inferences into the epidemiology and management of this infection. The study finds that the infection, which causes episodic abortions and growth issues in newborns, was not linked to various factors including last breeding date or medical treatment, but has a positive correlation with late breeding season and increased mare age.

Research Goals and Methodology

  • The aim of the study was to perform a detailed analysis of pregnancies affected by nocardioform-affected placenta, a type of placental infection in horses known as nocardioform placentitis.
  • The study involved 264 mares, with 145 suspected of having the disease based on pregnancy-related complications or postpartum placental evaluation, while 119 were healthy pregnancies.
  • The diagnosis of either suspected disease or healthy pregnancy was based on gross and histopathology done at the University of Kentucky Veterinary Diagnostic Laboratory.

Clinical Observations

  • Many of the diseased mares showed clinical indications of nocardioform placentitis, including premature mammary gland development, thickening of the placenta, and separation between the chorioallantois and endometrium.
  • Interestingly, vulvar discharge was not commonly observed in the infected mares.

Correlations with Nocardioform Placentitis

  • The disease was found to be associated with increased mare age, shorter gestation period, and lower neonatal weight.
  • The infection had no correlation with the mare’s last breeding date, pre- and post-breeding therapeutics, parity, prophylactic medications, or housing.
  • The occurrence of nocardioform placentitis did not affect the postpartum fertility of the mares.

Impact on Neonatal Outcome and Infection Transmission

  • The disease was linked to poor neonatal outcomes, like abortion and retarded growth.
  • However, the type of bacteria causing the infection didn’t appear to influence these outcomes.
  • Mares diagnosed with nocardioform placentitis didn’t seem to transmit the infection to other pregnant mares and didn’t have repetitive years of the disease.

Interesting Findings

  • The study found an interesting correlation between the size of the placental lesion and the last breeding date – mares bred later in the season had larger placental lesions.
  • While the causes of nocardioform placentitis continue to remain unclear, this study provides significant insights into the epidemiology of this disease, assisting in the management of affected mares.

Cite This Article

APA
Fedorka CE, Scoggin KE, Ruby RE, Erol E, Ball BA. (2021). Clinical, pathologic, and epidemiologic features of nocardioform placentitis in the mare. Theriogenology, 171, 155-161. https://doi.org/10.1016/j.theriogenology.2021.05.023

Publication

ISSN: 1879-3231
NlmUniqueID: 0421510
Country: United States
Language: English
Volume: 171
Pages: 155-161
PII: S0093-691X(21)00183-7

Researcher Affiliations

Fedorka, C E
  • Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
Scoggin, K E
  • Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
Ruby, R E
  • Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
Erol, E
  • Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
Ball, B A
  • Department of Veterinary Science, University of Kentucky, Lexington, KY, USA. Electronic address: b.a.ball@uky.edu.

MeSH Terms

  • Actinobacteria
  • Animals
  • Female
  • Horse Diseases / epidemiology
  • Horses
  • Placenta
  • Placenta Diseases / epidemiology
  • Placenta Diseases / veterinary
  • Pregnancy

Citations

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