Diagnosis and management of abnormal embryonic development characterized by formation of an embryonic vesicle without an embryo in mares.

This research aimed to study the incidence, characteristics, and risk factors associated with the abnormal embryonic development, specifically the development of an embryonic vesicle without an embryo, in mares through ultrasonography examination.

Research Methodology

• The research was conducted over a span of four years, from 1994 to 1998.
• A total of 159 pregnant mares between 11 and 40 days after ovulation were selected for the study.
• Ultrasonography was used to examine the mares, both with normal and abnormal embryonic development.
• Each conceptus, or products of conception from fertilization to fully formed state, was thoroughly examined and characterized.

Findings of the Study

• During the five breeding seasons, the incidence of abnormal embryonic development characterized by the formation of an embryonic vesicle without an embryo was found to be 4.4% represented by 7 out of 159 mares.
• The research found that variables such as age and breed of the mare or the type of semen used did not impact the development of embryonic vesicle without an embryo.
• Conceptuses were undersized significantly higher in the mares with abnormal conceptuses (5 out of 7 mares) compared to mares with normal conceptuses (2 out of 147 mares; 1.4%).
• An undersized conceptus was found significantly more in examinations of abnormal conceptuses (12 out of 27; 44.4%) in comparison to normal conceptuses (4 out of 448; 0.9%).

Conclusion and Recommendation

• The study recommends monitoring of the conceptus size in mares as undersized conceptuses are more likely to be associated with abnormal development.
• The use of transrectal ultrasonography is advised for mares on day 25 after ovulation to diagnose an embryonic vesicle without an embryo. In cases where an embryo is not identified, reexamination should be carried out at intervals of 1 to 3 days until day 30.