Hey all! How are you all doing this week? I’m feeling especially important and accomplished, as I successfully pranked all of the Springhill staff this week! It was a beautiful Thursday afternoon, and I had been lounging peacefully in the office as the last appointments of the days drew the ramp up on their trailers. I quickly and quietly slipped away, however, before the crew started the close the front door to keep us up for the night. As closing time approached, I could hear Marilyn (our new office manager) yelling my name and shaking the treats. Later on, I heard Dr. King pull in and she also spent about 30 minutes calling my name. I could hear her on the phone with a frightened Dr. Lacher, discussing my absence. She also called to see if I had hitched a ride home in someone’s trailer. I watched as she walked to the road, looking at black tire scraps and continuing to yell. Finally, I decided to give up my jib and came up to the clinic. Dr. King hugged me and yelled at me, then fed me treats, scolding and petting me some more. I was a little confused, but glad to be rid of the spiderwebs that had clung to my fur on my adventure.
Anyway, we are supposed to be discussing breeding. We have been discussing the many aspects of the cycle of the mare, from seasonality to the hormones involved, the appearance of the uterus and ovaries when the mare is in and out of heat. We will discuss more about the actual breeding in the near future (semen will be covered with the stallion), we are going to assume that your horse has been bred and it is time to look for a pregnancy!
14 day embryo
We typically suggest a pregnancy check at day 14, when the embryo is large enough to be detectable by ultrasound, but when it is in the stage of moving around the uterus. A horse embryo rolls around the uterus for an unknown reason – presumed to be associated with the mare’s recognition of her pregnancy – prior to finding a spot to nestle in. If there is any chance your horse has had a double ovulation, it is critical that your horse be checked between day 14 and 16 post-ovulation. This is the optimal time to reduce twins before the embryo fixes and implants at day 17-18. To reduce a twin pregnancy, the embryo is “pinched” or crushed, with the aim of allowing one of the two twins to survive. This is easiest when they are small and mobile.
This sounds awful, but you must remember that while twin pregnancies do occur and survive to delivery, it is extremely rare to have a pair of twin horses survive to a year of age. A growing foal demands that their placental surface cover all available surfaces of the uterus, so sharing simply isn’t tolerated. Twin pregnancies that aren’t reduced result in one or both foals aborting, or they are born mummified, dead, weak, and/or undersized, and many born alive die soon after birth. If having one healthy foal survive a twin pregnancy is lucky, having a pair is a miracle. The 14-16 day embryo is the best time to manage this condition.
Many older mares have cysts in the lining of their uterus. If we have seen your mare before, we have an idea of where her cysts are located along her ‘Y’ shaped uterus. Cysts and embryos can appear similar sometimes, but the primary difference is that cysts remain the same in size and location, and embryos move and grow. One can imagine a cyst as a peg on a pinball machine, where the ball (embryo) can be delayed, stuck for a moment, or stopped completely if there are a number of them in a group. If there is any question if the structure seen is a cyst or an embryo, a check in hours or days will usually reveal the answer.
Once a single pregnancy is confirmed at 14-18 days, we also recommend checking your mare at 25-30 days. At this time, we look for a heartbeat, which will confirm that the embryo is alive and well. If it is not, we recommend giving the horse prostaglandin to lyse the CL, terminating the pregnancy before the endometrial cups form. Once these structures form, if the pregnancy is lost, the horse will be finished for the season. It will take the rest of the breeding season for the cups to resorb and uterus to return to normal.
Well thanks for stopping by to read my Blog! Until next week, keep up with your own pranks, and stop by to give me some pets! May your litter box be clean and your food bowl full! 🙂
