Early detection of pregnancy in mares is strongly demanded by owners in order to maximize breeding efficiency and economic investment. The most reliable and earliest available tool for conceptus detection is ultrasonography. Other diagnostics include palpation per rectum and hormonal blood tests (i.e. estrone sulfate in serum or urine; equine chorionic gonadotropin in serum) as these methods are useful when examination by ultrasound (per rectum or transabdominally) is not possible or feasible.
Welcome to The Select Breeders Blog
Use of Ultrasonography for Pregnancy Diagnosis in the Horse
Genetic Preservation in Mares Utilizing TVA and ICSI
Early demise due to illness or injury can shorten a mare’s reproductive career. Additionally, subfertility can also have a negative impact on a mare’s ability to produce a foal. There have been a multitude of advances in the past 20 years that have allowed for the preservation of genetics in mares. Techniques such as transvaginal ultrasound-guided oocyte aspiration (TVA) and intracytoplasmic sperm injection (ICSI) have allowed us to produce embryos in vitro, circumvent subfertility in mares, and preserve genetics from mares that have died.
Breeding Soundness Exam of the Mare
To evaluate a mare's potential for reproductive success or failure, veterinarians often perform a "breeding soundness examination" (BSE). As the breeding season approaches, many owners may opt for a pre-breeding BSE to identify and address any potential reproductive issues prior to breeding. This examination is invaluable for estimating the likelihood of a mare successfully conceiving, carrying a pregnancy to term, and delivering a healthy foal. Pre-breeding examinations are usually performed early in the breeding season when the mare has just begun to cycle or, at the very least, is not in anestrus. Furthermore, the BSE provides veterinarians and owners with important information to determine whether a particular mare should carry a foal herself or whether she might better serve as an embryo or oocyte donor, as well as what breeding strategies are most appropriate for the individual mare.
Intrafollicular Oocyte Transfer in the Mare
In the equine breeding industry, many different assisted reproduction techniques (ARTs) are widely used to aid the management of equine reproduction. ARTs provide options to owners looking to obtain embryos from genetically valuable mares and/or stallions for whom conventional breeding management strategies are insufficient. This article provides a concise summary of several common ARTs, as well as information regarding innovative techniques just entering clinical use.
A Brief Overview of the Equine Oviduct
When considering common causes of infertility in the mare, the oviduct is one of the last places an equine reproductive specialist looks. Uterine infections, poor conformation and stallion subfertility are much more likely causes for a mare’s failure to produce a pregnancy. That being said, there are rare cases where oviduct pathology is suspected, and in the past few years there have been advances for oviductal treatment that are cost effective, safe and have restored fertility in some patients. This summary will highlight some unique features of the mare oviduct, discuss when to suspect oviductal pathology or dysfunction, and review some of the current treatments available.
High Prevalence of Latent Endometritis in Problem Mares: Effect of Activation and Treatment on Fertility
Beta-hemolytic Streptococcus equi subsp. zooepidemicus (BHS) is the most frequently isolated pathogen in the uterus of mares. However, in a large fraction (>50%) of subfertile mares there is no obvious reason identified. We recently demonstrated that BHS have the ability to reside deep in endometrium and may also gain intracellular access. The ability to escape and hide from the immune system allows BHS to cause long lasting, hardly detectable infections. In addition to this, we have shown that BHS are able to enter a dormant state where the bacteria can slow down their metabolism. Most antibiotics inhibit bacterial growth by disrupting the microbial metabolism which makes the dormant bacteria highly tolerant to antibiotics.
Unexplained Subfertility in Broodmares
Breeding season is just around the corner and most breeders dread the frustration of subfertility in certain broodmares. A thorough breeding history is key to diagnosing the cause of subfertility. Questions that address previous breeding management, stallion selection, and general wellness are important when performing a breeding soundness evaluation. Diagnostics such as trans-rectal palpation and ultrasound examination of the reproductive tract, vaginal speculum examination, digital cervical palpation, endometrial cytology and culture, endometrial biopsy, and hysteroscopic examination are useful in determining the cause of subfertility. Typically, a cause of subfertility can be determined utilizing the diagnostics mentioned above, but there may be some cases in which diagnostic test results are negative and yet a mare is still subfertile. So what’s next?
Progesterone Therapy for Pregnant Mares-Part 2: Common Questions
Thank you to Dr. Pat McCue from the Equine Reproduction Laboratory for last month’s article, Progesterone Therapy for Pregnant Mares – Part 1, in which he reviewed the formulations and use of progesterone therapy in mares. Dr. McCue did a yeoman’s task in outlining the formulations and principles of therapy available to veterinarians for the suppression of estrus, pregnancy support, and treating cases of suspected or diagnosed placentitis. However, the maintenance of pregnancy is by far the most common area in which we receive questions about supplementing mares with exogenous (therapeutic) forms of progesterone.
Progesterone Therapy for Broodmares: Part 1
In preparation for our annual SBS Affiliate meeting, I was speaking to Dr. Patrick McCue (my friend and mentor and honored guest speaker this year’s meeting) about the commonality of questions I have from clients. By far, the most discussed topic is supplementation of progesterone to pregnant mares to help them maintain a pregnancy. Many times, the questions stem from the necessity of such therapy, duration, and efficacy of supplementation. Sometimes, even with the best therapy, we fail to reach a good outcome, but the following discussion about the forms of supplementing progesterone is well worth a quick read for any breeder.
Measuring Hormone Levels in Mares
Endocrine diagnostics certainly have a place in the routine management of mares and stallions as well as in diagnosis of problems and diseases. However, there are likely more applications for measuring hormones in mares than stallions. Dr. Ed Squires will discuss the hormones tested in mares in this article and will then cover the testing of stallion hormones in a subsequent article.