Down to the Wire
Jacqueline T. Linkous, MRCVS
By JACQUELINE T. LINKOUS, MRCVS
June has to be my least favorite month of the year. It is incredibly hot here in north-central Florida and the bugs have arrived in droves. The breeding season is nearly at its end, and with the close of the breeding sheds looming, the race is on to get every possible mare in foal. The sinking feeling that comes with a negative pregnancy check seems ever more intense as the month drags on. Each positive pregnancy check comes with a sigh of relief.
To be fair, some mares simply foaled late and they are only now making their way to the breeding shed. Fortunately, the majority of foaling mares settle easily. This seems more true this year, perhaps because the stallions are not overworked in this slow economy. I have certainly seen my fair share of one-cover pregnancies this season.
It is the problem mare that puts the pressure on as the season ends. These include those that do not become pregnant after multiple attempts, and those that were pregnant earlier in the season and then found open on a follow-up pregnancy check.
Mares that do not get pregnant on multiple trips to the breeding shed are not uncommon. The mare’s uterus is meant to be a sterile environment. We take a uterine swab or culture from any mare being bred for the first time in a season. A negative culture slip is required by the breeding sheds for any maiden or open mare and is good for 60 days. A positive uterine culture means that the mare is harboring a uterine infection and will need to be treated with intrauterine antibiotics. A negative culture must be obtained before a “dirty” mare visits the shed. Any mare that is not pregnant after two cycles should be recultured in case she has acquired an infection during the breeding process. I recommend a culture on any mare that does not get in foal on her 30-day, post-foaling cycle, even if the foal heat was not used. Some mares have chronic infections that are difficult to resolve, or they tend to become reinfected due to conformational factors. All of these issues must be resolved before pregnancy will be achieved. Still, mares with negative cultures will fail to get in foal. This may be due to a poor cover by the stallion, but often there is no explanation.
Mares can be checked for pregnancy as early as 14 days from ovulation. Typically, I perform my pregnancy checks at 15 or 16 days post-ovulation. Follow-up pregnancy checks are performed at 30 days, 45 days, 60 days, and 90 days. These follow-up checks are important because early embryonic death can occur in any mare. Knowing that the early pregnancy did not survive allows us to send the mare back to the stallion before the breeding sheds close. Owners usually have a deadline in their minds about when it is too late in a season to breed back. They might forego the follow-up checks if they feel it is too late.
A negative follow-up pregnancy check brings difficult news for the owner and for me. It is frustrating to have to start all over with a mare that was previously pregnant. Didn’t someone once say that the definition of insanity was doing the same thing over and over again while expecting a different result? The breeding season can certainly invoke that feeling, especially by the time June is here. Regardless of the reason a mare is open, getting her in foal at this stage of the game brings us down to the wire!