Unfortunately, all mares do not react to teasing in the same manner, so one approach doesn't suit all. There will be mares which show themselves to be in season at the mere sight or sound of an approaching stallion, while others will show subtle signs that only can be detected by an experienced handler or veterinarian. Whatever the case, modern science has found no replacement for teasing to detect estrus in mares. In very small breeding operations, the teasing can be done with the breeding stallion, but this is a sure way to develop a frustrated horse which is difficult to handle and can become rank and overly aggressive. Needed is a teasing stallion that is aggressive, but not abusive to mares.
Teasers range from ponies to full-size stallions of varying breeds.
Normally, cycling mares should be teased daily with at least one stallion. Mares that have not achieved normal cycles and mares exhibiting the first day of diestrus should be teased with two stallions. The mare should be teased by the stallion head to head, at the buttocks, and at the external genitalia. Kicking, ears back, squealing, moving, and striking have been found to correlate negatively with estrus. In one large study, the combination of winking, squatting, and a failure to kick was found to be most predictive of estrus.