Lutalyse and Sulpiride

Estrus synchronization is a term used to describe the phenomenon of getting mares to ovulate at the same time, or close to the same time. It is slightly different from using desorelin or another agent to make one mare ovulate, because both mares are treated or monitored from the start. The product that is used the most, and is probably the oldest, is called Lutalyse. I have also used this quite a bit on dairy cows. Lutalyse is given to a mare intra muscularly and we gave 2cc of it. What it does is lyses the corpus luteum if a mare has ovulated recently, and essentially restarts the mare building follicles. The time given for her to come back into heat is about 2-4 days. If this is given to two mares, no matter what stage of follicle development they are in, you will know that they will both be coming into heat around the same time. Lutalyse is also given to donor mares. Once the embryo has been flushed from the donor mare, she may have follicles present and she will definitely have a corpus luteum. The CL is lysed and will bring her back into heat much more quickly than if her body is given the time to realize she is no longer pregnant. The process of bringing a mare into heat that has just ovulated is known as short-cycling, and is very helpful when you are trying to get many embryos from a donor mare during a season, or if you would like to breed more than one mare (or cow) at a time.

At my facility, another practice we had this year was administering IM injections of sulpiride to the recipient mare herd. When I googled the drug sulpiride, it came back with information that it is a drug used for schizophrenia and as an anti-psychotic. This was very interesting to me because on the farm, sulpiride is used to cause mares to begin to come into heat and grow follicles earlier in the year than they normally would. In the scope of our practice this is necessary because there are some donor mares that naturally start the breeding season early, so there are potential embryos in February that must have recipient mares. So here’s how it works; sulpiride inhibits the release of dopamine in the brain. This neuro-transmitter has been shown to control the time when an animal is not ready to breed. By stopping the release of dopamine, veterinarians have been able to cause mares to begin heat cycles much earlier in the year than they normally would.