Teasing mares can be a time-consuming and boring procedure, but it is essential if one is to detect when a mare is in estrus. 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.
The one-on-one technique has been used to greatest advantage at most breeding farms.
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. The good teaser is a male that will "talk" to mares.
Edward L. Squires, PhD, of Colorado State University, underlines the importance of teasing when he states:
"Inadequate or improper teasing constitutes a major cause of poor reproduction performance in the mares. 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.
"Eversion of the vulvar labia (winking), tail raising, squatting, and urinating have been shown to correlate positively with the presence of estrus. 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."
The manner in which teasing is conducted varies. There are some breeding farms where a stallion is merely led up and down the outside perimeter of a paddock fence containing a number of mares. If a mare comes forward and demonstrates the classic signs as articulated by Squires, she is either palpated or simply bred.
That technique has some definite shortcomings. First of all, there is a pecking order in every group of horses. If there are two horses--or 20 horses--in a group, the pecking order will go from the most dominant horse present to the one most dominated. Thus, in the above approach, the mare at the bottom of the pecking order could be in season, but would be afraid to approach the stallion if the dominant mare or others higher in the pecking order were positioned between her and the stud.
It would be much the same with the mare which does not show strong signs of estrus. She could easily be lost in the shuffle, with her mild signs of estrus going undetected.
The one-on-one technique has been used to greatest advantage at most breeding farms. Here an individual teaser is allowed to approach an individual mare. The normal procedure is to allow the pair to approach nose to nose, with the stallion then allowed to nuzzle and sniff other parts of the mare's anatomy.
If this is done without a restraining wall between the two, it can pose a danger to the handlers and to the teaser. Some mares are violent in their rejection of a stallion when in diestrus. They will strike, bite, and kick. Teasing over a wood barrier reduces the risk of injury to all involved.
"There are several teasing programs that can be used to identify mares in estrus," reports Martha M. Vogelsang, PhD, Texas A&M University. "When moderate to large numbers of mares must be teased, it is probably most efficient to utilize a system in which minimum handling is required. Such methods might include a group-teasing paddock with a cage for the stallion, or a long chute for mares to pass through while the stallion is led alongside. Both methods are relatively safe for mares, stallions, and handlers.
"In the cage group-teasing situation, mares are free to demonstrate estrus behavior or lack of it. The only disadvantage to this type of teasing program is when shy, timid mares will not approach the stallion or are not allowed access to the stallion by a dominant mare in the group. In this situation, it is probably best to tease such mares individually. The person responsible for estrus detection must be conscientious and perceptive in evaluating all mares so that they recognize those mares which might require individual attention.
"There are many ways to individually tease mares. Selection of which to use may depend on facilities, teaser stallion, or personal preference. If mares are maintained in stalls or paddocks, the teaser stallion can be taken to them for teasing over the stall door or paddock gate. An advantage here is that the breeding manager is assured of seeing each mare's response. The partition between mare and stallion should be secure. A solid partition to a height of four feet is preferred, rather than a paddock gate or wire or board fence which would allow injury to feet and legs if either individual pawed or struck (either of which is likely to occur during teasing).
"In any teasing schedule, mares should be given adequate time to react to the stallion and the surroundings. In group-teasing, using a stallion cage, mares need 15 to 20 minutes to allow all mares the opportunity to demonstrate their behavior. In hand-teasing, several minutes should be spent with each mare.
"Mares in intense estrus or those in diestrus or early pregnancy will normally display the expected behavioral characteristics quickly. Mares that are just coming into estrus may take slightly longer to exhibit any signs when exposed to the teaser stallion."
Vogelsang is a strong proponent of keeping complete records on the behavioral characteristics of each mare during each teasing session.
Following is her system for the scoring of behavioral estrus in mares, with the score being listed first and the behaviors it denotes following:
0--Rejection of stallion's presence (ears pinned, kicking, biting, or pawing at stallion) or complete lack of interest in stallion.
1--Not aggressive toward stallion, but looks away or is not interested.
2--Shows interest by facial expression and might approach stallion; slow to show interest. Mare might raise tail or exhibit some winking (eversion of the labia of the vulva). Mare might show these signs at a distance, or in close proximity to stallion.
3--More interest in stallion as demonstrated through facial expression, tail raising, flexion of pelvis (posturing), winking, and urination.
4--Intense interest in stallion as demonstrated by turning hindquarters to him, leaning toward him, and exhibiting continuous winking and urination.
When one considers the fact that only about 55% of the mares bred annually in the United States are estimated to produce live foals, it becomes instantly obvious why every positive step should be taken to insure pregnancy. Teasing is one of those critical steps.
A variety of factors is responsible for the poor reproductive performance of the modern-day mare.
Squires puts it this way:
"One obvious factor contributing to this low reproductive efficiency is the seasonal occurrence of estrus, which precludes the possibility of conception during a large part of the year. Although methods for expanding the breeding season by inducing estrus during the winter anestrus have been evaluated, none has yet been proven to be very effective or practical. Some progress has been made to regulate the cycle during the spring transitional period.
"The average duration of estrus in normally cycling mares is approximately seven days. In the early part of the breeding season, however, estrus may be erratic and extend to as much as 20 to 30 days. In addition, as a result of hormonal imbalance during the transition from winter anestrus to the normal breeding season, ovulation may not occur. Ovaries of mares during the early transition period are characterized as small and hard with only small follicles. In contrast, ovaries of mares during the latter part of the transition period contain numerous medium to large follicles (20 to 40 millimeters). It is not until one follicle is selected to mature that the mare ovulates and a normal cycle is initiated.
"The erratic estrus behavior leads to low pregnancy rates during February and March. Normalization of the estrous cycle earlier in the breeding season would result in considerable savings in terms of time, labor, and stallion usage, and would improve reproductive efficiency.
"Another problem associated with equine breeding is the uncertainty of the time of ovulation. Ovulation can occur at any time during estrus, but normally occurs at the end of the estrus period. Much time is consumed by regular teasing to detect estrus behavior and by rectal palpation to determine the time of ovulation."
When the teasing program has resulted in the mare showing signs of estrus, it is time for rectal palpation to aid in predicting the time of ovulation. For stallions which are heavily booked, it is imperative that the number of covers on individual mares be kept to a minimum.
While teasing is imperative in detecting estrus, there are steps the mare owner can take to assure that the mare will come into estrus at an early date.
A key element, declares Scott Bennett, DVM, who operates Equine Services in Simpsonville, Ky., is diet. While emaciated mares have little chance of becoming pregnant, Bennett sees more problems with obesity in his practice.
"Horses should be fed individually," he says, "and they should be fed by weight of feed, rather than coffee can measure. I'd rather see them on the thin side rather than too fat."
He also advocates that a mare should be kept as free of stress as possible as she approaches the breeding season.
"A good worming and vaccination program is important to reduce stress. The mare should at minimum be vaccinated for rhinopneumonitis and influenza every three months. Worming should also be done every three months minimally."
Lighting the Way
Prior to beginning the teasing process, mare managers might make use of artificial lights in order to bring the mare into estrus earlier. The increase of daylight in early spring is primarily responsible for initiating normal cyclic activity in the mare.
It is thought, says Squires, that the increasing amount of light perceived by the retina of the eye inhibits secretion of the hormone melatonin from the small pineal gland in the brain.
"Removal of the inhibitory effects of melatonin allows the hypothalamus in the brain to release a hormone called gonadotropin releasing hormone (GnRH). This hormone stimulates the pituitary gland at the base of the brain to secrete the gonadotropic hormone, follicle stimulating hormone (FSH).
"FSH stimulates the growth of one or more ovarian follicles, the structures within the ovary that contain the eggs or ova. As these follicles develop, estrogen is secreted. Estrogen acts on behavioral centers in the brain to stimulate estrual behavior in the mare."
It all begins with light. The purpose of using artificial light in the winter is to trick the mare's reproductive system into thinking that spring has already arrived.
Vogelsang puts it this way:
"Currently, the simplest and most effective management protocol for bringing mares into heat prior to the natural breeding season is the use of extended day length. By imposing an artificially long day on mares beginning in late November or early December, the hormonal mechanisms that control estrous cyclicity are stimulated such that mares will begin to ovulate in mid- to late February (rather than March to April).
"Although different lighting schedules have been studied, a lighting program that supplies 16 hours of light to eight hours of dark seems to provide a consistent response. The additional light can be provided by placing mares in stalls or paddocks where there is sufficient light in the late afternoon, and maintaining the light artificially until approximately 11 p.m. The amount of light necessary to elicit photo periodic stimulation is at least 3-foot-candles at the level of the horse's eye. A 200-watt incandescent bulb provides adequate light in the average stall.
"It is important for the mare owner to understand that extending the day length does not provide an immediate response, nor does it eliminate the transitional period between anestrus and the ovulatory season. A behavioral response can be seen 30 to 60 days after the program is initiated, with first ovulation occurring 60 to 90 days after the lighting program begins.
"It should also be noted that exposure to extended day length stimulates shedding. Depending on the climate, mares in extended day length programs may need shelter and/or increased nutrient intake during this period."
Estrous cycles also can be manipulated with the use of exogenous hormone treatments that shorten or prolong diestrus or enhance ovulation. The most commonly used hormones are prostaglandins, human chorionic gonadotropin, and progesterone.
Despite what research has revealed about the functioning of the equine reproductive system, along with the development of new drugs, tools, and procedures, nothing has been found to replace old-fashioned teasing. Male-female contact is essential before the mating process, either natural or artificial, is carried out.
Interestingly, the teasing of mares and the breeding of them in the wild state are simple and straightforward by comparison. Each band of wild horses has a dominant stallion which will breed all mares within the group except his own daughters. When spring arrives and the mares begin showing signs of estrus, he checks or teases them regularly. It is rare that the wild stallion will attempt to mount a mare unless she is ready to accept him. And most interestingly, he seems to have an uncanny ability to pinpoint when she is ovulating. It is not unusual for mature wild stallions to cover a mare only once during a seven-plus day cycle.
By gently teasing her on a daily basis, he knows when the time is right to breed.
Whether in the wild or in the most sophisticated domestic breeding program, nothing is more important than regular teasing during the breeding season.
About the Author
Les Sellnow is a free-lance writer based near Riverton, Wyo. He specializes in articles on equine research, and operates a ranch where he raises horses and livestock. He has authored several fiction and non-fiction books, including Understanding Equine Lameness and Understanding The Young Horse, published by Eclipse Press and available at www.exclusivelyequine.com or by calling 800/582-5604.
POLL: University Equine Hospitals