Mare Teasing

With breeding season fast approaching, the Broodmare Farm Manager takes us behind the scenes and into the barns as teasing begins. Teasing is an efficient process that can determine a mare’s estrus cycle and allow for the effective timing of stallion covers.

The estrus cycle, a recurring period of sexual receptivity and fertility, occurs seasonally when the length of daylight is long. While naturally occurring estrus begins in spring, exposing mares to artificial lights starting in early December allows estrus to begin in time for the breeding season in mid-February.

Determining the estrus cycle starts in early December with daily teasing. Teasing is when a teasing stallion is put in close proximity with a mare so that one can look for signs of ovulation. Teasing stallions are adult males of multiple breeds including Thoroughbreds and quarter horses.

While there are several techniques for teasing, at Stonestreet, the one-on-one technique is used. The teasing stallion is shown to the mare either by opening the window between adjacent stalls with the stallion in one and the mare in the other or by walking the stallion through a barn and stopping at each individual stall with the stall door ajar. This technique ensures the safety of the stallion, mare, and handlers as mares can have strong reactions to a stallion when out of heat.

The reaction of the mare is observed and recorded. When a mare is in any stage of estrus, reactions may include ears pointed forward, tail raising, squatting, winking vulvar lips, and urinating, referred to as “breaking down”. When a mare is out of heat, reactions may include ears pinned back, kicking, striking, squealing, and moving back from the stallion.

Dr. Thomas Riddle of Rood and Riddle Equine Hospital developed a numerical system to classify a mare’s reaction, allowing the broodmare manager to effectively communicate with the veterinarian. The classifying system is as follows:

0 – Out of heat
1 – Change of attitude (for example: quieter, less ear pinning)
2 – Winking vulvar lips
3 – Breaking down (urinating) after a short time
4 – Breaking down immediately

This system is very helpful, but not every mare is honest when in estrus. Many mares will progress from a 1 to 4 and others may show a 1 while actually being at the peak of ovulation. In order to determine an accurate schedule, the Broodmare Farm Manager is present for each teasing so that he can become familiar with each mare’s teasing behavior. Maiden mares, a term used to describe one that has never been bred, are most likely to be deceptive when teased.

Currently, mare teasing is performed on barren mares and maidens with teasing for mares in foal beginning five days post delivery. When an estrus cycle is determined the Broodmare Farm Manager will decide when further tests should be performed, including palpation and ultrasounds, and ultimately when a mare should be sent to a stallion.