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

I. F. Canisso, K. A. Beltaire, S. J. Bedford-Guaus

Research output: Contribution to journalArticlepeer-review


Premature luteal demise or luteal insufficiency is not well characterised as a cause of pregnancy loss in domestic species, including horses. In this report, a mare inseminated with cooled-transported semen at our facility returned for a routine pregnancy diagnosis at 15 days post ovulation. Ultrasonography per rectum revealed endometrial oedema and the absence of visual indication of a corpus luteum on either ovary. Nonetheless, an embryonic vesicle small for the gestational age was identified. Daily oral altrenogest treatment was implemented immediately. Serum progesterone concentration was 0.67ng/ml, which is below the threshold considered adequate for pregnancy maintenance in the mare. Examinations were repeated at 17, 25, 30, 39, 49, 72 and 120 days post ovulation. At 25 days post ovulation the embryonic vesicle presented normal development for the gestational age. In addition, sequential blood samples were collected to measure progesterone, equine chorionic gonadotrophin and oestrone sulphate concentrations. Although progesterone concentration did not exceed 2ng/ml until 72 days post ovulation, all other results were unremarkable and a healthy filly was born uneventfully at 344 days post ovulation.

Original languageEnglish (US)
Pages (from-to)97-100
Number of pages4
JournalEquine veterinary journal
Issue number1
StatePublished - Jan 2013
Externally publishedYes


  • Altrenogest
  • High risk pregnancy
  • Horse
  • Luteal insufficiency
  • Luteal regression
  • Pregnancy rescue

ASJC Scopus subject areas

  • Equine


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