Breeding Season is Around the Corner!

As winter approaches, it is time to start preparing for the 2016 breeding season! During the fall and winter, the length of daylight shortens. This shortened photoperiod causes hormonal changes in your mare that signals her to enter into a period of noncyclity or “winter anestrus.” This period of anestrus will persist until the late spring when longer periods of daylight will allow her to retransition into a normal 28 day estrus cycle. In our area, most horses left to their natural transition will not begin cycling normally until mid May! This causes our breeding season to be rather short and limits our number of opportunities to get your mare in foal. This becomes a particular problem if your mare has any roadblocks to the breeding process such as infection, persistent transition, hemorrhagic follicles, early embryonic loss, etc which can take up valuable time to clear up or treat. For this reason, we recommend introducing artificial photoperiod to ANY mare that is likely to be bred. By introducing extended artificial photoperiod to mares in early December, we should create enough hormonal signal to have each mare out of transition and cycling normally by mid February. Even if you don’t want an “early” foal, transitioning your mare early allows us to have ample time to do any necessary pre-breeding diagnostics such as uterine culture or biopsy, treat any persistent infection or problem from the previous season, and ensure that your mare is ready to go whenever you decide the time is right. Please see below for guidelines on how to introduce this artificial photoperiod.

Option 1

  • Start date: Dec 1
  • Add lights to the END OF THE DAY! (Extra morning light is not effective at inducing transition)
  • Mares need 16hrs of light/day to initiate transition
  • Turn on lights from 5pm-11pm. You may want to set up a timer to minimize cost.
  • Make sure there are no dark “escapes” in the stall such as a window or door that your horse can hang her head out of. Her eyes have to see the extra light!
  • Light should be bright enough to read a newspaper in the darkest area of the stall.

Option 2

  • Equilume Mask
  • Start Date: Dec 1
  • The Light Mask is designed to be activated once at 4pm on the first day of use. It will then automatically turn on at the same time each day and automatically switch itself off at 11pm.
  • Similar design to a fly mask, but more durable.
  • Allows horses to remain in turnout without stall restriction.
  • To read more about EquiLume, also check out this write-up.

If you have any questions about preparing for breeding season or introducing artificial photoperiod, please call the office for a consultation with Dr. Gray.

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