Now that the season is well and truly underway, many breeders will obviously be considering the options available for achieving pregnancies in difficult breeding mares. Those mares which have not had a foal for the last two years are a particularly difficult challenge, especially if there is no obvious reason for their infertility.
In recent years, following on from research in the human medical field, temporary blockage of the oviduct has become recognised as a cause of infertility in mares.
Mares which continually fail to conceive despite being mated to a fertile stallion, undergoing normal ovulations and having no evidence of disease of the uterus or cervix, may be suffering from blocked oviducts.
The oviduct is a narrow tube that runs from the ovary to the uterus, and it is where fertilization of the mares "egg" by the sperm occurs. Blockage of the oviduct is due to an accumulation of debris from previous ovulations or pregnancies. The blockage will often allow the passage of sperm, due to their very small size, but not allow the passage of the developing embryo, causing it die in the oviduct.
It has been shown that the application of prostaglandin to the oviduct will cause it to contract and flush the debris from the oviduct.
Laparoscopy is a surgical technique, much like arthroscopy, where a long camera is placed into the horse's abdomen to view the oviduct, uterus and other internal organs.
A laparoscopic technique to view and treat the oviduct with prostaglandin has been developed in recent years and very exciting fertility rates have been achieved in previously infertile mares. The technique is performed 4 days after ovulation with the mare standing and under sedation. In more recent years we know the technique can be done at any time in the mares oestrus cycle and some clients are deciding to do the procedure before the season starts. This procedure does not distress the mare and is very well tolerated. The Scone Equine Hospital have also recognised that tight bands can cross the oviduct, potentially blocking the duct and that these can be cut at the time of surgery.
Scone Equine Hospital surgeons have performed the procedure on over 120 mares with a pregnancy rate of over 80% achieved every year since the procedure was introduced in 2009. Considering the mares that underwent the procedure had a pregnancy rate of 0% for the previous year this is an amazing result. Of the mares that conceive after surgery, up to 50% do so on the same cycle as the surgery.
Interestingly, it was not just old mares that appeared to require this surgery. Of the 120 horses that have undergone the procedure 25% are maidens and these mares have a similar pregnancy rate, in fact, often better than the average.
When dealing with the problem of difficult breeders, it is very rare for new procedures to arise that achieve conception rates of 80% in previously infertile mares. This advanced surgical technique provides a treatment option for broodmare owners who are struggling with mares which fail to conceive for no apparent reason.