Breeding horses has come a long ways in the last 50 years. Veterinarians have been able to overcome many of the obstacles presented when breeding horses with advancements in artificial insemination and embryo transfer. However, there are still times when infertility of either the mare, stallion or both prevent getting foals on the ground. The most recent advances in assisted reproductive technologies, Ovum Pickup and Intra-Cytoplasmic Sperm Injection (ICSI), have allowed us at Weatherford Equine Breeding Center (WEBC) to take the next step in overcoming these obstacles with some promising results.
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Effect of Number and Timing of Equine Frozen Semen Inseminations on Fertility
Further expansion in the use of frozen semen is dependent upon developing simplified strategies for insemination. SBS has developed a timed insemination protocol where mares are only examined once per day during estrus and inseminated at 24 and 40 hr after hCG or 30 and 40 hr after GnRH. This approach allows frozen semen mares to be managed similar to those bred with cooled shipped semen. A couple of arguments against this approach with frozen semen is that it takes too much semen when mares are bred twice in one cycle and that if the mare is inseminated more than once per cycle the fertility will be lowered because of post-breeding induced endometritis.
Heat Stress and Equine Reproduction
During those dog days of late summer and the end of the breeding season, most of us who work in equine reproduction are ready for a break. You are left with those difficult mares that didn’t settle earlier in the season and stallions that may be growing tired of breeding. Mares may not cycle as predictably or conceive as readily and stallions may be tougher to collect or exhibit a decrease in semen quality. One of the factors that can contribute to these problems is heat stress. As ambient temperatures rise, stallions and mares may experience disruptions to normal reproductive function as a result. This article will briefly describe some of the effects of heat stress on mare and stallion reproductive function.
Retained Placenta in the Mare
Retained placenta (also known as retained fetal membranes) is the most common post-partum complication in mares. Typically, expulsion of the placenta occurs shortly after birth and it is considered retained if it is not expelled within 3 hours post-partum. The prevalence of retained placenta varies from 2 to 10% of foalings and can be as high as 30 -54% of uneventful births in Friesian mares. Retention of the placenta in mares should not be overlooked. Appropriate diagnosis and treatment should be quickly applied to prevent secondary, life threatening, complications.
Splitting Doses of Frozen Semen
“I just purchased one very expensive dose of frozen semen from this incredible stallion. Is it OK to split the dose and breed two mares to try and get two foals?” or “The stallion owner only provides one dose per heat cycle and my vet would like to use a timed insemination protocol. Is it OK to split the dose and inseminate twice on the heat cycle?” At SBS we have heard these questions or some variation of them many times over the years. The answers are not simple ones. This blog article will follow up on two previous blogs that are also important in understanding the issue. See the recent blogs What Exactly is a Dose of Frozen Semen? and What is Progressive Motility?
Placentitis in the Mare - Causes, Diagnosis and Treatment
Placentitis, an inflammation of the placenta usually caused by an infectious agent, has emerged as a leading cause of reproductive loss in the equine breeding industry. This has a large economic and emotional impact when the pregnancy progresses until close to term but unfortunately ends in abortion or the birth of a small ill-thrifty foal. The placenta is composed of the amnion, which surrounds the fetus and the chorioallantois that attach to the endometrium of the mare. These structures protect the fetus and provide gas and nutrient exchange allowing the foal to grow. When placentitis occurs it usually affects the chorioallantois compromising the foal because there is a loss of attachment of the placenta to the endometrium or the presence of infection and inflammation. In this article, Dr. Karen Wolfsdorf of the Hagyard Equine Medical Institute, discusses the causes, diagnosis and treatment of placentitis in the mare.
What is Short Cycling a Mare?
It seems daily that I am asked by clients to bring a mare into heat at a desired time to facilitate breeding, show schedules, stallion availability, synchronization with other mares, maximize early season breeding dates, or line up recipient mares with donor mares. For such a common request, and in fact, a common procedure, there are certain cases when knowing the nuisances of manipulating the length of diestrus in the mare can make or break the overall success of a reproductive cycle. In this blog article Dr. David Scofield reviews the process of short cycling mares.
The Pros and Cons of Equine Frozen Semen
The advantages and disadvantages of utilizing equine frozen semen are debated by stallion and mare owners alike. Will I continue to show my stallion or retire him to the breeding shed? Is there an international market for my stallion? What if my stallion is injured in an accident or suddenly dies? Is my mare a suitable candidate for breeding with frozen semen? Is it true conception rates with frozen semen are lower than those when using cooled semen? These are just a few questions to ask when considering whether to utilize equine frozen semen.
Parturition in the Mare
In our newsletter last month, we talked about getting organized and ready for foaling out your mare (click here for this news article). Being prepared for the foaling process is of paramount importance, in order to have an enjoyable and successful outcome for the mare, foal, breeders, owners, and attendants. As you are preparing your barn for the foaling, don’t forget that the mare has a chorus of events taking place internally to prepare her body for parturition, transition to lactation, and uterine involution. Whether these events are noticeable or not, they are a necessity for the proper progression of labor and delivery. In our blog article this month Dr. Scofield reviews the stages of parturition and summarizes the hormonal events that are occurring with your mare during this incredible physiological process.
Progesterone and Estrogen Therapy (P&E)
Managing the equine estrous cycle is a common procedure performed by many broodmare managers and veterinarians. Copious research has elucidated many aspects of the equine estrous cycle and allowed veterinarians the tools to manage a mare’s cycle to provide the optimal breeding times, effectively use artificial insemination, induce ovulation, synchronize mares, induce superovulation, advance the onset of the breeding season, terminate pregnancy, as well as a manage a host of other reproductive conditions and diseases. In this article Dr. David Scofield reviews the use of progesterone and estradiol (P&E) therapy in the mare.