By Dr. James McCall




Lesson Three




          Assuming that pasture breeding is not the best breeding solution for your operation the first problem that must be addressed for hand breeding solutions is to determine when the mares are receptive towards breeding.


           Every year for the 30 years that I taught horse reproduction to college students majoring in equine science, I ask them to memorize a list of ten signs that signaled the sexual receptivity in the mare. Included in that list are the following:


                                      1. Frequent urination


                                      2. Frequent contraction of labia major (winking)


                                      3. Mucous secretion


                                      4. Slight swelling of labia


                                      5. Change in body odor of the mare


                                      6. Vaginal vascularity


                                      7. Increase in follicle size


                                      8. Cervical dilation


                                      9. Seeks company of other horses


                                      10. Teaser becomes more excited in her presence


          Some of these signs are visually apparent and others are easily determined through rectal palpation.  Most of the time, the students take these “symptoms” of estrus to be simple and straightforward.  Actually, however things are seldom as simple as they seem.   Consider the following incident.


          One of my students was a young man who was especially interested in mare management. He worked hard as an undergraduate to develop some proficiency in breeding farm skills and, upon graduation, was hired as a stud manager. In this capacity, one of his responsibilities during breeding season was to determine the sexual receptivity of the mares coming to the court of the farm's stallions. To the amazement of the veterinarian, the new kid on the block could identify mares exhibiting split estrus, double follicles not ready to ovulate, and mares with single follicles ready to rupture before they came through the palpating chute.


     This impressive display of intuitive knowledge did not go unnoticed. The following year, my former student was offered a position as general manager on a larger breeding farm. When breeding season rolled around, he again found himself responsible for the teasing charts on the new farm. By April, it was evident from the charts and the vet checks by palpation that the person in charge was not doing an adequate job of determining when to bring mares to the breeding shed.


           I was asked to try and isolate the difficulty, and so I questioned my former protégé as to what he thought the problem might be. How did he explain the difference in his job performance this year compared to his previous success the year before?


     His answer was to the point. "Last year I used the same stallion all the time and teased each mare individually. This year I am working with a new teaser and using a group teasing system."


          "While I understand there are some subtle differences in these techniques," I said, "I can't see how this change should have made such a difference in your ability to evaluate the reproductive status of the mares in your care. You were the best rookie I ever saw at observing and evaluating mare behavior."


     "That's not exactly true," he responded. "I hardly ever looked at the mare. I just watched that old teaser stallion. After spending so much time with him, we developed a good communication system. By paying close attention to him, I learned to let him tell me the reproductive stage of each mare. If the old horse did something that confused me, it usually meant that the mare had a problem. I just interpreted for the vet what the teaser stallion had told me."


          It was apparent that my former student had learned one of the ten signs of sexual receptivity in the mare (the stallion is more excited when the mare is in heat), but he needed to study the other nine. Yet he did point out how useful it could be if one could develop an astute understanding of the teaser excitation level in the presence of mares to be bred.


           As an aid to clarifying the teaser stallion behavior, I developed a scoring system that is based on the duration and intensity of the horse's interest. By using this system, it is possible to compare the teaser's behavior with that of the mare's behavior as a more precise indicator of the optimum time for breeding.





    0.  The horse is brought into the presence of a mare and finds his advances unwelcome. Within a minute, the teaser is either looking for other distractions or wants to eat grass.




Teaser Stallion Score: 0. The stallion finds his advances unwelcome and will quickly become distracted.




   1.    When the mare is not totally repulsed by the teaser, the stallion may tease in short bursts but with long pauses in between. These pauses may expand in length until the horse is no longer interested. The horse may get an erection but it will not be maintained.


Teaser Stallion Score: 1. The stallion teases in short bursts with long pauses in between.




     2. When a mare shows a mild interest in his advances, the stallion may           become more excited and very vocal with bursts of stallion squeals and           chuckles that may last for several minutes.


Teaser Stallion Score: 2. The stallion becomes more excited and very vocal, with squeals and chuckles lasting several minutes.




  3.    When the mare shows strong signs of receptivity to breeding, the stallion becomes aroused and passionate toward her. He will continually court the mare with intense interest. He may give a flehmen response, squeal,       and paw the ground, after which he will feverishly return to the blowing, nibbling, and talking. The stallion will get and maintain an erection.


Teaser Stallion Score: 3. Aroused, the stallion will continually court the mare.



4.   The stallion is most aroused just before a mare ovulates.  He is pumped full of adrenaline and exhibits more intense characteristic behaviors as described above in number 3. It may be almost impossible to divert his attention from the mare. He will continually tease her and not want to be led away.



Teaser Stallion Score: 4. Intense interest that is almost impossible to divert.


     It is important to note that all stallions are individuals and have their own unique style and level of aggressiveness during courtship. For instance, most two-year-old colts do not have the stamina for teasing or the interest that a three-year old might. Three-year-olds, however, seem to have nothing on their minds but sex.   They become very aroused at the slightest exposure to a mare of any type. They are likely to maintain this interest with very little or no encouragement from the mare.


           Even with older horses, there is a wide range of libido within two standard deviations of the norm. The stallion manager must be able to read and understand the behavior of his particular teaser stallion if he is going to get the most information available to him during the act of courting mares. Well-developed powers of observation are very necessary tools in an efficient and highly successful breeding operation.


     Compare the Teaser Stallion Scoring System with one developed for mares.





     0. Shows absolutely no signs of interest in the stallion. Rejection is           expressed by attempts to leave his presence; kicking, squealing,     wringing her tail, etc.



Mare Teasing Score: 0. Shows absolutely no signs of interest in the stallion.




 1.      Passive resistance. Rejects his advances but not his presence. Appears to enjoy his conversation but not his advances.



Mare Teasing Score: 1. Rejects his advances but not his presence.




 2.     Likes the attention of the stallion but will not stand to be mounted. May urinate, raise her tail, or have contractions of the vulva (winking);   however, her behavior lacks intensity and she does not strike a breeding stance.



Mare Teasing Score: 2. Likes his attention but will not stand to be mounted.



3.      Adores the advances of the stallion. Will urinate (throw-off), raise tail,           wink, and allow herself to be mounted. Increased intensity of behavior.



Mare Teasing Score: 3. Adores the advances of the stallion.



4.      Mare becomes aggressive, seeking out the attention of the stallion. Exhibits all the behaviors of 3 heat breeding score and will back up to the stallion requesting breeding (hitting a breeding stance).



          During the estrus cycle, the mare will begin as a “0” and move up to a “4” upon ovulation.  She will then move back down the scale to a “0” signaling that she is out of heat.


          Also, keep in mind that mares slip between these categories of behavioral estrus. To calibrate this movement a plus or a minus sign may be added to the score. For example, a mare either moving into estrus from a "0" or slipping out of estrus from a "1" may be designated as a "1-." She does not completely resent the stallion, but she does not find harmony close to him.


     Obviously, there is some subjective judgment to be used in scoring mares. The more familiar one is with the individuality of a mare, the more accurate her heat score will be.


          For some shy, silent-heat type mares, a "4" may be described as an intense gaze at the stallion and a desire to stand one foot closer to him. On the other hand, there are mares that appear never to slip below a "1" even when they are pregnant. They are always willing to stop and chat politely with any stallion passing by.


          It is for these odd mares that the behavioral scoring of the teaser stallion becomes an extremely important tool in deciphering exactly what is going on with these intriguing and sometimes confusing creatures known as broodmares.




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Develop a chart which compares the scoring system used for a teasing stallion to the scoring system used for mares.  On this chart, explain the behavior related to each score.