Equine herpesviruses: type 3 as an abortigenic agent.

This study explores the effects of injecting equine herpesvirus type 3 (EHV3) into a pregnant mare’s amniotic cavity, which resulted in abortion. The presence of EHV3 in various organs and fluids of the foetus, along with the lack of usual genital tract lesions in the mare, provide evidence for EHV3 as an abortigenic agent in horses.

Introduction

In this study, researchers examined the possibility of equine herpesvirus type 3 (EHV3), a specific strain of a virus found in horses, being responsible for inducing abortions in pregnant mares. The research aimed to understand the direct impact of EHV3 on the pregnancy of mares and the pathology caused by the virus in the foetus.

Methods

• The experiment was carried out by inoculating a mare 6-7 months pregnant with the EHV3 strain.
• The period of abortion, post-inoculation, was observed to be 11 days.
• The mare’s physical condition was monitored for typical signs of coital exanthema, a disease caused by EHV, in the genital tract following the abortion, which were not found.
• On the other hand, serological tests were conducted to identify the presence of EHV3, providing positive results and confirming successful inoculation of EHV3.

Results

• The aborted foetus showed signs of disease specific to EHV3 involvement, including placentitis, focal ulcerative dermatitis, necrosis in lung areas, and severe gastritis.
• Additionally, the presence of EHV3 was confirmed in different parts and fluids of the foetus, such as the small intestine, spleen, lung, skin, thoracic and abdominal fluid, stomach fluid, and specifically, the placenta and its associated fluids.
• The histological observations provided crucial evidence at the cellular level with findings including interstitial pneumonia, diffuse hepatitis, generalised myositis, and extensive vascular necrosis, along with degeneration of various epithelial cells.

Conclusion

This study provides comprehensive evidence of EHV3 being able to cause abortion in mares, which contrasts the typical belief that EHV3 mostly impacts the genital tract, causing coital exanthema. The research elucidates an unexplored pathology of EHV3 and adds immensely to the existing knowledge base of equine herpesviruses. Further research in this area would enhance understanding and eventually help in the establishment of effective intervention measures for pregnant mares infected with EHV3.