Introducing a New Horse to a Group

Written by Jane Jackson, KPA-CTP

Earlier this summer I purchased a new horse. Before bringing him to our farm, I gave a lot of thought to how I would introduce him to the five equines already living on our farm. I allow my horses as much social contact as possible given that horses are social animals. “Although husbandry conditions for horses have improved over the last decades, many horses are still kept singly with limited or no physical contact to other horses. This is surprising, given the fact that keeping horses in groups is recognised best to fulfil their physical and behavioural needs, especially their need for social contact with conspecifics, as well as to have a beneficial effect on horse-human interactions during training.” (Hartmann et. al, 2012). In one study, “results indicate that based on physiological and behavioural measures incorporating social contact into the housing design of domestic horses could improve the standard of domestic equine welfare.” (Yarnell et. al 2015).

The separations and introductions in this project were for behavioral purposes only. I did not need to medically quarantine the new horse from others, as I had a five-year immunization history on him and knew the husbandry practices of his farm of origin. Anyone without this information should prevent all contact for longer than I have done here.

A common approach for introductions is to allow horses to meet (sniff each other) over a fence, which usually involves some squealing as well as possible striking (kicking forward with front hoof) (see Diehl, 2016). If either horse is loose, it may also involve one or both turning hind ends to the other and kicking out with hind feet. A sturdy fence usually protects them from injuring each other, as well as preventing further chasing. These protected greetings can be done immediately or after a couple days with the new horse on the property. During this waiting period, horses can be placed in stalls next to each other or turned out in adjoining enclosures to get to know each other without full access. In a study involving young Danish warmblood mares, “pre-exposure of young horses in neighbouring boxes may reduce ‘contact aggression’, especially biting, in the paddock and ‘bite threat’ shown in boxes may help to predict contact aggression when horses are later turned out together.” (Hartmann et. al, 2009).

I wanted to avoid potential problems and try to set things up for the best chance of success, meaning the least stress or potential for harm, be it physical, mental or emotional. I didn’t really want my horses to “work it out” if that included kicking, chasing, or other behaviors that would be unpleasant for any horse involved.

Another factor that encouraged me to be cautious is that the five equines I already owned had lived together for five to ten years, and for three of them this encompassed their entire lives. They weren’t accustomed to horses coming and going as occurs at some facilities. I had introduced only one other horse to the group during that time, an aged mare who lived here for the remainder of her life. Her death had caused a considerable amount of stress to one of my homebreds, so I knew there were some pretty tight bonds in the existing group. I wanted to give this new horse the opportunity to move in with the best chance of developing calm relationships, so they could co-exist happily as one group, rather than having to separate anyone into smaller groups.

My plan was to introduce the new horse very gradually, over many weeks. I had set things up to keep him physically separated, while still fairly close and in sight. I was hopeful that by putting this extra thought and effort into my introductions, I would facilitate a smooth transition.

Things did not go as I thought they would. While I do believe that minimizing full-body contact for longer periods of time is advantageous, I did not expect the stress exhibited by the existing horses when separated from their familiar companions. Fortunately I was able to adapt my plan when this became apparent, without requiring major environment changes.

Settingstable map

  • Two buildings: one four-stall barn, where the existing horses could be confined (two ponies sharing a stall) and one 10-foot by 20-foot three-sided “pony shed” where the new horse would have shelter.
  • Each building had an attached sacrifice paddock (the grass being sacrificed to heavy equine traffic). The new horse would have full access to his sacrifice paddock (“2”). The equines in the barn could be confined to their stalls but when in their sacrifice paddock (“1”), also had access to a shed roof extending from the side of the barn, which I will call the “run-in shed” to differentiate from the “pony shed” where the new horse was. Both sacrifice paddocks had sturdy fencing, one being 5-foot round pen panels and the other being 5 feet of high tensile woven wire topped with a strand of electric wire. This fencing provided a secure barrier between horses until I was ready to allow them contact.
  • There are two additional non-grass areas I had available. One was a sand round pen (“Sand Pen”), also with 5-foot round pen panels. The other was my 70-foot by 150-foot sand arena.
  • The two sacrifice paddocks were separated by 75 feet. This allowed me to put a good distance and two solid fences between the new horse and the others from the start.
  • Grass pastures surrounded these buildings and paddocks. I utilize a rotational grazing system where I separate large fields into strips. The equines have access to one strip for a few days, then move to a new strip. Each grass strip leads back to respective sacrifice paddocks with access to shelter and water. The strip fencing is one strand of electric rope. I had no intention of allowing horses to meet or interact over this, so I planned to use plenty of physical distance in the initial days to cut down on temptations to get to each other.
  • I would then decrease the distance between the grass turnouts as I moved them every couple of days.


The summer schedule is that equines are in stalls (or pony shed) during the heat of the day when the flies are most miserable. In the late afternoon they are turned out in grass paddocks for a few hours until dark. They don’t need 18 hours of grass a day, so just before dark I bring them into sacrifice paddocks where they spend the night sleeping or interacting. In the morning they go back out on grass for a couple hours while it’s cool before coming into stalls again.

Sometimes all five are together, and sometimes I separate the pony mares to lower quality grass access.


I will call the new horse by his initial, “W.” I have assigned the others a number in the order they were introduced to W. I thought that would be an easier way for readers to follow than trying to remember names. I ranked them all in order of resource guarding tendencies and introduced them from bottom to top. Descriptions of each are as follows. I include physical descriptions because age, size, and gender all impact interactions, while breeding can affect reactivity. Also, none of my horses wear shoes, which decreases the likelihood of severe injury with any kicks that made contact with another horse.

W: 16.1 hand, 10-year-old New Zealand-bred Thoroughbred gelding. The new horse had been exposed to many sights and sounds in his life, living on three different continents before he was #5 and living in various boarding and home facilities since being brought to the States. As a result, I expected him to accept his physical transition smoothly. At the time I purchased him, W was living out in a field 24 hours a day with a group of horses, including some young ones. I was told he was the one who got first pick of hay piles, but was not a bully. This history was a benefit to me since not all horses have experience living in a large group of different ages. I certainly did not want a bully. He was larger than any of my others, in both height and substance.

#1: 14 hand, 15-year-old Pony of the Americas gelding. #1 is the least likely of my equines to resource guard anything: food, space, or company. If threatened or cornered, he rapidly exits and keeps his distance. He does not pair up with any of the others for food, play, or fly protection. He is also the least reactive, so I count on him to be a calm influence in many situations, thus he was my first choice to share space with W.

#2: 15.3 hand, 9-year-old Thoroughbred/warmblood gelding. #2 is the most sociable of all my equines. He will share any resources with anyone. He can approach any of the others who have resource guarding tendencies and is accepted. He will make mild attempts to keep ponies away from a hay pile but will share the water tub, human attention, or shelter without a problem. #2 enjoys chasing games and biting games at times when there is no food available. He and #4 play long and hard when turned out together. Because of #2’s history of being accepted by all the others, I was a little concerned he might blunder into W’s space and get into trouble, so I wanted to observe W’s reaction to someone else before introducing #2.

#3: 12 hand, aged Welsh cross mare. Like #1, she is highly unlikely to resource guard anything and tries hard to keep her distance. As the smallest and a mare, she’s likely to squeal and kick if she feels herself threatened by being cornered or chased (thus, she is #2’s favorite for the chasing game). She often holds herself quietly away from any group, especially if there is conflict.

#4: 14 hand, 11-year-old Quarter Pony gelding. #4 is the equine most likely to resource guard anything. If resources are plentiful, #2 can usually share anything with him, but if resources are limited or when access is first gained, #4 will occasionally warn him off and #2 needs to sneak his way in carefully. Because both #4 and W were accustomed to first pick of resources, I wanted to be very careful in how I introduced them.

#5: 13 hand, 11-year-old grade mare. #5 is the daughter of #3 and they share space and other resources well, although Mom gets first pick of food.  The only thing #5 resource guards is her mother, but she does so vigorously. The others can take a hay pile or space in the shed from her, but if she perceives another individual getting too close to her dam, she will gallop across the field to intervene and repeatedly double barrel (kick with both hind legs at once) the offender, regardless of who it is. They all back off. Due to her extreme reactions, she was the last one to be introduced.

The plan

As I stated, I wanted to introduce W to everyone very gradually. To start, I was going to keep him completely separate physically. My hypothesis was that giving everyone time to see, smell, and hear each other for a couple weeks at a distance, would result in little to none of the striking, kicking, and chasing when I eventually allowed them physical contact.

After this time of separation, I planned to introduce each one separately for a day or two during turnout. Grass was abundant, so there would be no need for resource guarding during their time together, which would be limited and supervised. When it was time to come back to sacrifice paddocks, W would again be separated so there would be no need for anyone to challenge for shed space, water, or hay.

horse in stable

W with his haynet

The Process

When W arrived, the others were in barn stalls with hay. I put W into the pony pen with a full haynet hanging in the pony shed. He was underweight, so I planned to keep hay in front of him to serve as a pacifier as well as a method of weight gain. Everyone was looking, listening, and smelling, but quiet, according to plan. They had about 2 hours before turnout time.

W was kept separate from the others for the following week, although by day #4, I allowed some protected sniffing.

My first unexpected result came on the second morning when the well-worn tracks of W’s pacing back and forth along the fence line indicated to me that he was not content in solitary confinement.

I had been told he was fine when living alone previously, but I should have expected the possibility of upset for four reasons.

  1. Even though he had lived alone previously, his most recent experience had been in a group of horses.
  2. Due to the high quality of my grass, compared to his previous living situation, I did not give him 24-hour access to grazing, which is calming to a horse. He had hay when confined to the pen but not grass, which is both more appealing to a horse and a more natural and time-consuming form of eating.
  3. I know that there is a difference between a horse living alone and a horse pastured alone when other horses are in sight. When truly alone, they can appear calm, but if there are horses in sight, they tend to call to the others and try to get to them.
  4. I have had problems with horses being worried in that shed and pen previously. We sometimes have deer and moose traffic on our driveway behind that shed, which is obviously concerning to horses when they aren’t used to it. Additionally, my barn cat loves to spend time in the trees behind the shed. He comes out to sharpen his claws on the back of the shed, making a racket that is frightening to anyone inside when they can’t see what is making the noise. The tracks W left from pacing all night were not along the fence closest to the other horses. They were opposite the shed, which led me to believe the pacing might be related more to fear than wanting to get to the others.
stable ground

Evidence of pacing

Since my plan was based on W living alone and that was my only other shelter, I crossed my fingers and left him there. I would have liked to pick up the shed and move it elsewhere, but that was obviously not practical. Some mornings he was more upset than others, and I became anxious to get him some company. I began to consider a more rapid introduction plan.

The following table charts the progression and results of the first week.

Day Setup Observations
1 PM turnout Geldings in far left Grass Paddock 1, pony mares in Sand Pen, W in Grass 2. #2 exhibiting lots of movement- racing, bucking, high headed staring at W. When brought in to Sacrifice 1, Equines #2 and #4 watched W carefully over gate.
2 AM turnout Equines #1-#5 in Grass Paddock 1.

W in Grass Paddock 2.

Tracks in pen indicate W was pacing during the night.

W whinnies when others come in.

2 Midday Took W to Arena to allow him to explore. Equines #1 and #2 watched closely over Dutch doors.
2 PM turnout Equines #1-#5 in Grass Paddock 1.

W in Grass Paddock 2.

W cantered around a bit when others went out.
3 AM turnout Equines #1-#5 in Grass Paddock 1.

W in Grass Paddock 2.

When the others came galloping in from pasture, W only turned from his grain bucket to look.
3 PM turnout Equines #1-5 in Grass Paddock 1, with access closer to W

W in Grass Paddock 2

Allowed Equines #1-#5 to spend some time in temporary alley, closer to W. Lots of watching and smelling.
4 AM & PM turnout I tried various turnout options to allow others closer access to W. I still did not want contact but hoped proximity would help calm W’s occasional whinnying and pacing. Quiet
4 Midday I brought W into barn for first time. Others were confined in stalls with grills closed. I gave W a bath in wash stall, then put him in a stall while I had that horse in wash stall. Then all went to respective grass turnouts as above. W pulled toward each stall as we passed, and the others sniffed through the grills (#4 sticking his nose out feed hole). I did not allow nose-to-nose contact on the way in, but did after the bath. Equine #2 and W had nose to nose contact possibilities while W was in stall but W was most interested in looking out over the Dutch door out into Sacrifice Paddock 1.
5-7 uneventful
8 AM turnout #1 in Grass Paddock 2 with W first full contact #1 paced the fence separating him from other horses, trotting and cantering 5-10 minutes. Kept his back to W. Then grazed.
8 Midday Hand walked W down road Lots of whinnying from everyone. W high-headed and looking/pulling back toward barn.

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After one full week of keeping all equines physically separated, the greetings through protected contact led me to believe we were ready to introduce shared turnouts. While there had been great interest in each other and plenty of sniffing, there were no squeals, strikes, or kicking of walls. On day 8, I put #1 out with W for morning turnout. This was my second surprise, and it was a shocker. I expected #1 to avoid contact with W if possible and as long as he was left alone, to graze quietly. Instead, he paced the fence that separated him from getting to his familiars. He trotted and cantered back and forth, demonstrating more stress than I have ever seen from him in all the years I’ve owned him.  W was not chasing him, but grazing quietly, although he did pick his head up to watch #1 occasionally.  W tried to interact with a little sniffing, but #1 kept pacing. I expected #1 to quit any second, so continued my chores while watching. Just when I was about to intervene, #1 started to quiet, stopped to grab a few bites, then paced, then grazed some more, and finally settled.

As a result of #1’s unexpected stress, I decided to try a different combination. Since #2 is my most social individual, that afternoon I let W and #2 meet each other through an open window in #2’s stall grill. #2 arched his neck and all four nostrils were very active, but it was without squeals or strikes, so the next afternoon I let them meet over a gate.

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In this video, you can see #2 arching his neck, which is somewhat conformationally based for him, but also indicates a state of arousal and excitement. Eyes were wide and he showed busy nostrils, but W walked away in less than 30 seconds. #2 continued to follow, but once W was next to the fence with the hot wire on top, #2 could not reach over it. Since #2 did not have a history of being a threat to anyone, and W seemed to have lost interest, I opened the gate and allowed #2 to go out with W.

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6/28, Day 9

#2 came out flinging his head around, which is typical for him when he is excited. He immediately approached W’s side, stopping short of touching him. At that point W turned to sniff #2’s forearm, and #2 lifted that leg. When young horses meet older horses they will sometimes lower themselves by bending a leg and dropping down. I’m not sure if this was what #2 was doing or if it was a defense to avoid having his leg bitten. He then backed away, neck still arched and ears alert. W sniffed his forearm again with the same response from #2. As #2 turned, his head passed over W’s neck, putting him in a potentially vulnerable position, although #2 did not actually bite his neck (a fighting tactic). Nonetheless, W gave a little squeal and small strike out with his front leg. #2 increased his speed of retreat. He did not kick out with hind feet as he left. W did not pursue him. They spent the remainder of that turnout time together, cautiously sniffing at times. What was most interesting to me was #2 hanging close to the barn, rather than going out to the good grass that W quickly discovered.

I continued my introductions the following day by putting #3 out with W in his grass paddock in the morning.  Here again, #3 clearly indicated she did not want to be with this strange horse when her friends were elsewhere. #3 usually keeps her distance from conflict and is not one who frets when separated.

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6/29, Day 10, 7am

As this video shows, #3 was not a happy pony as she trotted around with her head high, looking frequently toward the others. She too calmed in time, but by this point, I was seeing a pattern that told me that my existing horses were exhibiting more stress at being separated from their familiars than they were due to any direct contact with W. That was uncharacteristic of all of them. The only individual who usually showed stress at separation was #4, so I abandoned any thought of introducing him to W separately, as well as my plan of introducing #5 to him separately.

Instead, I decided to try #2 and #4 together out with W. #4 is the one I was most concerned about due to the resource guarding problems.  This presented a conundrum. I wanted an abundance of resources when I turned them out to avoid guarding.  This would have meant turning them out on the grass. My concern was that #4 has been known to blow through fences when wound up for any reason, and I also wanted to be able to catch anyone easily if things didn’t go well. I had to make a choice. I chose to turn the three of them out in the sacrifice paddock where the fence was secure and I could more easily remove one by slipping him in through a stall door in a pinch. Instead of excess food resources (grass underfoot), there was no food to guard.

It turned out I was right to be concerned about #4.

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6/29, Day 10, 5:30 PM

There is a lot of detail in this video.

  • W sniffed #4’s forearm as he did when first meeting #2, but #4 immediately vocalized deeply, stomped that front leg, wheeled around with pinned ears and kicked at W with both hinds. W turned away.
  • W approached #4 again while #4 stood still. W turned his head away once on approach. #4 again vocalized deeply, wheeled, and lashed out with his feet three times, and with more height to the kicks. This seems to me less of a warning and more an attempt to make contact. W quickly backed out of range.
  • W trotted a few steps, keeping his hind end pointed toward #4, possibly ready for defense. He looked away and walked away. #4 followed him, mostly at a walk but did trot a few steps. I wouldn’t call it chasing but he definitely followed, rather than allowing W to keep distance between them.
  • W stopped and allowed #4 to sniff his hind end, then turned. This is followed by another nose-to-nose sniff, although detail is hard to see with #2 in the way.
  • W turned and left again. #4 trotted, shaking his head. W elevated his head and trotted, then turned to meet #4, but #4 placed himself with his butt facing W.
  • W sniffed brush. #4 approached again.
  • W sniffed #4’s nose, not his leg this time, then pulled away. #4 vocalized and swung his butt to W, but didn’t kick out this time.
  • W walked away again.
  • At this point, I thought it should be settling down, as W had walked away from #4 several times.
  • I watched this for ten minutes, however, and #4 continued to follow W around, vocalizing and turning his hind feet to kick at him numerous times. This surprised me since nothing like that happened when they sniffed through stall grills. When they moved into the shed doing this, I decided it was too risky (no escape routes), and separated them.
  • Incidentally, I first saw this extreme reaction from #4 when he was less than a day old. If his mother moved while he nursed, he would pin his ears and kick her in the jaw with both hind feet as she grazed. #2, on the other hand, always got along with others at all ages.
  • I did find #2’s behavior throughout this process interesting. He sometimes put himself between the others. Other times he kept himself out of the way but did not leave, instead staying close to #2 and sniffing him a couple times.

The next day I put #4 in the arena while W, #1 and #2 grazed along the outside. If W had chosen to approach the arena fence, he could have sniffed with #4, but #4 was not able to get directly at W. W, #1 and #2 did well together grazing quietly and I decided to continue putting others in with W in groupings so that the long-term farm occupants did not become stressed being separated from their familiars. W seemed to be comfortable with any of them, so I was not worried about him being cornered or chased.

On day 11, I put the pony mares (#3 and #5) in that same grass area with W and #2. #5 watched W closely and kept herself between W and her dam (#3), and there were no problems. Because I had larger groups than I’d originally planned, I left the paddock as a large area, allowing room for freer movement of more equines, rather than maintaining the grazing strips.

Day 12, I added #4 in with everyone on grass. This was the first time the entire group was together. Because everyone except #4 seemed to be OK, it would have been an option to just keep him separated. Instead, I chose to use the plentiful grass and the open space as a way to avoid resource guarding either of those things. I confined them away from shelter for this turnout time so that was not a concern. While I did not see conflict the first day, I did notice that the next time W had some surface wounds on his legs that made me think that #4 had kicked him. #4 This was discouraging, as I had tried to avoid that with my whole experiment. They were not deep, and while leg injuries on horses can never be treated casually, it’s not unusual to have horses living in a group show up with “dings.” It’s the price we pay for allowing them to be in a social group. The only way to completely avoid this is to keep them in solitude and that is not healthy either. I hoped that my carefully managed daily access would give W and #4 opportunities to develop a social bond without the extreme behaviors of the first interaction.

The only other protective behavior that could be concerning was #5’s guarding of #3.  Because #3 kept herself away from the group when at all possible, I thought #5 would not feel she was threatened in this environment.

My long-term goal is to have everyone together in the winter.  They will have a large field with multiple hay bags on nice days, but in foul weather, shed space is limited. I did not want to wait until then to try them all together. Instead, I managed the time they were together to brief periods when I was home and could keep an eye on things. I made sure the spaces were open and I never left W and #4 together in the dark or when they wanted to be in a shed.

I also organized everyone into pairs when not on grass. Because #2 is both careful and better accepted, he has become W’s companion in sacrifice paddocks. During turnout, I rotate the others in pairs with them: #3 and #5 for morning turnout and #1 and #4 for afternoon turnout. That keeps the ponies from eating too much grass and minimizes crowding in the grass strips. That setup turned out to be successful and is what I continue today.

#2 comes in with wounds but they are on his neck and face, a result of “face biting games” such as those seen in this video.

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As you can see, #2 instigates it as often as W, so the wounds are just from rough play and no one is being unevenly harassed. There are some vocalizations, and plenty of mini-rears, but no striking with front feet nor kicking out with hinds. #2 approaches W’s hay piles cautiously, and is allowed on the fringes.

W has been here for two-and-a-half months and now is likely to pin his ears at the others, as well as bite and/or chase them in tight spaces. If he and #4 meet in the alley, they pass each other cautiously. When it is time to come in, W is first in line. #2 has maintained his ability to be close, but not too close, if grain is waiting for W in his stall. On grass, they all graze together peacefully, and even in close proximity to W.

W has learned to approach me in any turnout situation like the rest do, and allows the others to be close to me and him; I ensure that the resources of my attention and pocket contents are plentiful. Whether this has affected his relationships with others I do not know, since I have nothing to compare it to. Since #2, #4, and #5 were born and raised here, I would say that their very different guarding tendencies do not indicate that training lifestyle equalizes relationships outside of human interactions.

Interestingly, when turned out together, #1 is frequently closest to W. They are opposite when it comes to resource guarding, so it’s interesting that they are close. #1 did not have anyone he hung out with before W’s arrival.  #2 and #4 love to play together while #3 and #5 have their mother/daughter relationship. Unfortunately, W and #1 have very different dietary and shelter needs, so I don’t see making them a pair of their own.

With fall here, I plan to make the strips wider; the grass will become less plentiful as the weather changes, and I hope to get all six together for a couple months of final grazing before I have to start feeding hay in piles. I still have concerns about sharing shed space come winter. Ideally, I’d have another shelter accessible from a turnout area so I could keep everyone in pairs. Instead, I will have to continue to monitor interactions as the seasons change, and make adjustments to the schedule if further social limitations are needed.

While I did not accomplish my desired goals of eliminating stress and injuries, I will never know if they could have been worse had I not been so cautious. My five equines behaved exactly as I expected, with the exception of their odd behavior when separated from the others. I keep going back to all the situations when they have been separated for other reasons with no stress. I do not know if W, who has now shown himself to be a presence to yield to, was somehow communicating that in a subtle way to the others that I could not see. Perhaps his presence simply raised overall stress levels on the farm so that all the others wanted the safety of their familiars.

This project did give me a realization of how unrealistic we expect horses to be in their introductions. New situations bring out different characteristics in individuals, which can result in renegotiating terms. A sure way of avoiding stress and the potential for physical injury may be impossible, but it’s our responsibility to minimize these when we can. Protected contact between horses is a challenge due to their size and strength. Striking and kicking through a fence can be equally or more injurious as without one.

The introduction to a new farm is abrupt when transporting a horse via trailer, rather than a more gradual approach. Even the most idyllic farm environments lack for space and resources when compared to the open plains. Facilitating equine introductions requires us to balance many factors and be ready to adapt as needed.


Diehl, Nancy. “How to Introduce Horses.”, #23 June #2016

Yarnell, K. et al (2015) Domesticated horses differ in their behavioural and physiological responses to isolated and group housing. Physiology and Behavior 143, pp. 151-157.

Hartmann, E. et al. (2009) Social interactions of unfamiliar horses during paired encounters: Effect of pre-exposure on aggression level and so risk of injury. Applied Animal Behaviour Science 121(3), pp.214-221.

Hartmann, Elke et al. (2012) Keeping horses in groups: A review. Applied Animal Behaviour Science 136:2, pp. 77-87.


Jane Jackson is a trainer of horses, dogs, and people. She is a Certified Training Partner with Karen Pryor Academy, an approved coach under Alexandra Kurland, and a Level 3 TAGteacher. She trains out of her Bookends Farm in Sheffield, Vermont, and travels to conduct clinics.