Premature luteal regression in a pregnant mare and subsequent pregnancy maintenance with the use of oral altrenogest.

The research paper details an unusual case of a pregnant mare with premature luteal regression, a condition that might usually result in pregnancy loss. However, using a treatment of daily oral altrenogest, the horse was able to maintain her pregnancy and give birth to a healthy filly.

Introduction

This study is centered on a single case of a pregnant mare suffering from premature luteal regression. This condition isn’t well studied or understood in domestic species, including horses, but it’s usually associated with potential pregnancy loss. In this case though, the mare was able to maintain her pregnancy and give birth to a healthy offspring, thanks to the use of oral altrenogest, a synthetic progestational agent used in horse breeding.

Methods

• The mare, after insemination with cooled-transported semen, returned for a regular pregnancy check at 15 days post ovulation. Ultrasonography revealed signs of abnormal pregnancy such as endometrial oedema and absence of visible corpus luteum on ovaries, indicating premature luteal regression.
• An embryonic vesicle small for the gestational age was identified, suggesting the pregnancy was still viable. The mare was immediately put on a treatment of daily oral altrenogest.
• The mare’s progesterone concentration was also tested and came out as 0.67 ng/ml, which is below the threshold for maintaining pregnancy in a mare.
• The mare was monitored continuously, with repeated examinations and collection of blood samples to track the levels of progesterone, equine chorionic gonadotrophin, and oestrone sulphate.

Results

• Subsequent tests revealed that despite the initial complications, the embryo showed normal development by the 25th day post ovulation.
• Even though the mare’s progesterone levels didn’t exceed 2 ng/ml until the 72nd day post ovulation, all other results, including the levels of other hormones, were normal.
• At 344 days post ovulation, the mare gave birth to a healthy filly.

Conclusion

The research concludes that in instances where mares show signs of premature luteal regression, oral altrenogest treatment can successfully maintain the pregnancy and lead to the birth of a healthy offspring. More research is needed to further understand the condition and the role of altrenogest treatment in such cases.