Recent advances in equine reproduction.

This paper discusses recent developments in the field of equine reproduction, including the influences of seasonality on ovulation, the changes in hormone levels during pregnancy, and advancements in pregnancy diagnosis and termination methods.

Ovulation and Seasonality

• The study reveals that mares usually do not ovulate during the winter season. It is the increase in daylight length during spring which triggers ovulation, hinting towards a direct link between seasonality and the mare’s reproductive cycle.
• The research also mentions that unserved mares, mares that have not mated, have a buildup of ova in their oviducts.

Pregnancy and Hormones

• During the period of gestation, structures known as corpora lutea multiply and then simultaneously regress around mid-pregnancy.
• It’s also noted that the levels of plasma progesterone, a hormone vital for maintaining pregnancy, rise towards the end of pregnancy while oestrogen levels fall.

Techniques for Pregnancy Management

• The paper states that methodologies exist for the early termination of pregnancy as well as for inducing parturition (the process of giving birth).
• Pregnancy can be diagnosed through rectal examination or by an immunological assay that detects a specific hormone known as pregnant mare serum gonadotrophin.

Potential Pregnancy Complications

• The phenomenon of service at the foal heat (the first heat after delivery of a foal) is associated with a higher incidence of early embryonic death.
• It is found that twinning is the most single significant cause of abortion in mares.

Other Reproductive Issues

• The study also points out that spontaneous prolonged dioestrus (a phase in the estrous cycle) is fairly common in summer, but can be effectively treated.
• Bacterial endometritis, an inflammation of the endometrium (the inner lining of the uterus), mainly results from the secondary pathogenic activity of the organisms found in the normal uterine flora. This condition can be accurately diagnosed by examining an endometrial smear, stating that methods of treating this condition have improved.

Male Reproduction

• Recent research has also found that reproductive functionality in male horses is also seasonally dictated.
• Another significant finding in this study is the ability to now accurately determine the presence or absence of undescended testis in horses.