Skip to content

What's Wrong With My Mare?

by Dr. Frederick Harper
UT Animal Science Department

Posted December 26, 2001

After weeks of winter weather, we think that spring has arrived when we get one day of sunshine.

But the mild days in late winter can be frustrating for broodmare owners who have open or barren mares. One of the most common questions is, “What’s wrong with my mare?”

Well, the answer is rather simple, even though the broodmare owner doesn’t like it. Nature takes its time. Several factors are at play.

Human intervention really messed up the horse-mating industry. Years ago in England, it was decided that all registered horses would have a common birthday of Jan. 1. No matter when a foal is born this year, it’ll be a year old on Jan. 1, 2002. But owners want their mares to foal early in the year based on the idea that bigger is better and early foals are bigger.

Herein lies the major problem. Nature doesn’t work on this timetable. Mares don’t mate until the days get longer in the spring. Length of daylight, as well as nutrition and warmer weather are key factors in nature’s process.

In the winter most mares become anestrus. In other words they don’t have estrous (mating) cycles like those that occur in spring, summer and early fall. Spring is a transition period during which the mare’s reproductive system must gear up for mating and pregnancy.

In the spring transition the mare’s reproductive system is unpredictable, giving owners ulcers and sleepless nights. Some mares in spring transition exhibit behavioral estrus (heat), which may last only a day or maybe for several weeks. During spring transition mares don’t ovulate. Mares cannot become pregnant until they ovulate, which normally doesn’t occur until about April 7. Mating the mare before this time is a waste of time and money.

What’s an owner to do?
Artificial lights can fool the mare into thinking it’s spring. But to be effective you have to put them under lighting at least by Dec. 1.

Hormone programs may aid in shortening the transition period. But only your veterinarian or a reproductive equine specialist should administer such programs.

Most mare owners probably just need to cool their heels and wait on nature to get “Old Molly” cycling regularly.

This isn’t a bad plan. Most foals are born in April and May anyway. Nature planned births when pastures are green and the weather milder. Management of foaling mares and newborn foals is easier and less risky at this time of year too.

Owners planning to use shipped cool or frozen semen need to put these orders on hold until their mare(s) are reproductively functional. Mares that you’ll transport to the stallion can stay home in a known environment until ready for romance.

Use the next 60 days to make sure that mares are healthy and in moderate body condition in preparation for nature’s intended mating season. Where practical use ultrasound or palpation to determine when the mare will ovulate. Mares usually have three to four large follicles (larger than 30 mm) before their first ovulation.

More Stories

  • Latest Issue WHYIR 20

    Read More
  • Latest Issue 3 1 31

    Read More
  • Walking In The Smokies stall deadline approaching

    The Walking In The Smokies Horse Show, scheduled for April 8-10, 2021, in Pigeon Forge, Tennessee is preparing for their first annual show and would like to send a reminder to anyone needing stalls that the deadline is March 15. Please contact Lexi Stinnett at 828-550-8520 to reserve stalls on the show grounds. Read More
  • Trainers' Show announces judges

    The Walking Horse Trainers’ Association National Trainers’ Show will be held at Calsonic Arena in Shelbyville, Tenn. March 18-20, 2021. Judges for the three-day event will be Wayne Dean, Newton Parks and Johnny Puckett. Read More
  • USDA prepares for 2021 show season

    The USDA recently conducted their virtual HIO training course for the 2021 show season. The USDA and industry recently received the final report from the National Academies of Sciences (NAS) and some of the recommendations in that report are communicated in the new processes the USDA will implement in 2021... Read More
  • WHOA hosts virtual awards ceremony

    On Saturday. February 20th, the Walking Horse Owners’ Association (WHOA) held their National High Point awards for 2020 on their WHOA Facebook page with winners who chose to be zooming in to accept their awards... Read More
  • WHOA to host virtual awards ceremony on February 20

    The Walking Horse Owners’ Association (WHOA) will recognize their award winners from the 2020 show season during a virtual awards ceremony on Saturday, February 20, 2021. The show will be broadcast live on WHOA’s Facebook page beginning at 6 pm central time. Read More
  • FAST Spring Showcase announces judging panel

    The FAST Spring Showcase is pleased to announce that John Fikes, Newton Parks and Sam Sorrell will judge this years’ two-day event. The show will be held at Calsonic Arena in Shelbyville, Tenn. April 16-17, 2021... Read More
  • Obituary – Kimberly Woods

    Kimberly Lynn Woods, age 47 departed this life on Sunday, February 14, 2021 at the University of Kentucky Medical Center in Lexington, Kentucky... Read More
  • WHAA annual barn party rescheduled due to inclement weather

    There will be a lot of great items to auction as well as breeding fees to some of the top stallions in the industry and training fees for many of the top trainers. Everyone is encouraged to bring your young horses to preview for the upcoming show season. Read More