This blog is a step by step account of how I introduced fly spray to Madagascar. It is presented as an example of an actual training scenario that describes how I chose which approach to use and how to transition from one type of reinforcement to another.
I bought Madagascar when he was 4 years old. He had already been started under saddle and when I visited him, he seemed fine with routine horse handling and care. But, soon after he arrived at my farm, I realized that while he tolerated many things, he wasn’t actually that comfortable with most of them.
Fly spray was one of those areas where I thought Madagascar would be ok, but he wasn’t. I didn’t discover this until the following spring because he arrived after the first frost in October. There were very few flies and I didn’t need to use fly spray. In retrospect, I wish I had tried it in the fall, so that I could have worked on it over the winter. But, I had plenty of training projects and wasn’t thinking that far ahead.
In mid-May the flies came out and I thought I had better see if he was comfortable with fly spray. We had a regular routine of grooming in the wash stall. I brought out the fly spray, showed it to him, stood next to him and sprayed away from him. He retreated into the far back corner. Ok…
I’ve worked with a lot of horses that don’t like spray bottles and/or the smell and sensation of fly spray, so I thought teaching him about fly spray would be pretty straightforward. My usual training strategy for this is to isolate out the different components (the sound, smell, feel) and introduce them one at a time. I’ve written about this in my blog “What Can I Train? F is for …” under Fly Spray.
I started doing my usual progression:
- I filled a spray bottle with water and sprayed around him, without directing the spray at his body. I started in front of him so he could clearly see what I was doing and then changed my position over several sessions until I could stand anywhere near him and spray at the ground or to the side.
- I put fly spray on a towel, let him smell it and rubbed it on his shoulders and neck, starting in an area where I knew he was not sensitive to touch and then slowly working toward being able to do this on other parts of his body.
- We had to sort out some details, but what worked the best was to spray the towel while facing away from him, turn toward him and wait for him to orient toward me, touch where I wanted to wipe, then wipe with the towel.
- I decreased the distance between him and the towel so that when I was spraying the towel, a little mist “might” touch his coat.
- Note: I did this in his usual grooming area. I could have started somewhere else and/or had him at liberty but in this case, I felt that the grooming area was a known environment and associated with a high rate of reinforcement and he would be most comfortable there. Later, I did change locations but I still think starting in the grooming area was a good idea.
He did great until we got to the last step. As soon as he felt the fly spray, he would quiver and then move away. I’ve had other horses that were sensitive to the sensation of fly spray touching their skin, so I knew that this would probably diminish over time. But, I had learned that he was unusually sensitive to touch on some areas of his body. I didn’t mind spending the time it took, but it was spring, the flies were out, and I wondered if there was a way to help him get accustomed to it more quickly.
I considered my options:
- I could continue with the towel method and slowly increase the amount of spray that touched his coat directly. This approach would rely on the premise that continued exposure in small amounts would lead to improved comfort with the procedure. Eventually I would fade out the towel by making it smaller and smaller and/or replacing it with a touch to indicate where the spray would land.
- I could add a start button behavior so he could tell me when he was ready for me to spray him. Start button behaviors are useful because they allow the horse to control when an event (the spray) happens. Control is very reinforcing for most horses and if they are given choices about how and when something happens, they are usually more comfortable with the whole procedure.
Start buttons also provide useful information for the trainer because if the time interval between the delivery of the last reinforcer and the horse offering the start button behavior increases, the trainer should consider why the horse is hesitating before offering the start button behavior. You can read more about start button behaviors in my blog What Can I Train? S is for … (look under start buttons). - I could change the environment so that the sensation of the spray was diminished. Getting the horse wet is one way to do this. A wet horse will not perceive the spray on his coat in the same way a dry horse does. This approach would work well if the horse was no longer concerned with the smell or sound of the spray, but just sensitive to the sensation of being sprayed.
- I could add a distraction so that he got used to the spray while he was paying attention to something else. Usually, I don’t like using distractions as I want the horse to be fully engaged in any training that I am doing with him, but there are times when using distractions can be useful. I am more likely to use them if I know I don’t have time to fully prepare the horse and the procedure is new, but not painful.
These were all viable options, but I was drawn to the last one – not because it was “better,” but because I had been reading about “masking” in an online course I was taking. In masking, the food reinforcer is presented in a way that distracts the animal from the potentially aversive stimulus. It’s not classical conditioning or counterconditioning because there is no deliberate pairing, but if done well, the overall experience is a positive one for the animal. According to what I read, masking can be effective if the reinforcer is sufficiently distracting and the stimulus is only slightly uncomfortable.
I’d never tried masking the way it was described in the course and was curious to give it a try. The fly spray issue seemed like the perfect opportunity. I didn’t think Madagascar was scared of the fly spray, but he behaved more as if he was uncomfortable with the physical sensation, so I categorized it as mildly aversive. I knew I had a very distracting and unusual reinforcer available – fresh spring grass. With masking in mind, I thought it would be interesting to see if he would ignore the fly spray if I allowed him to graze.
Before I describe how the training went, I want to mention the importance of predictability. With many husbandry behaviors, I find it helpful to set up a very predictable pattern so that the horse knows exactly what to expect and in what order. Later, when the horse is comfortable with what is being done, I will add variations so that I have more flexibility in how and when I do the behavior. This will make the behavior stronger and more flexible. In the case of fly spray, I usually spray the horse in the same order every time, going from less sensitive areas to those that are more likely to result in unwanted behavior.
In the next section, I describe the training steps I used. I have divided the training up into 4 phases and included how many days I spent in each phase. I am not recommending a specific time frame, that’s just how it ended up working out for me. I was in no hurry, and I enjoyed hand grazing him, so I took my time transitioning to being able to spray him in the grooming area. I’ve also found that when introducing any stimulus that might be aversive, I get better results if I do shorter sessions that are spread the sessions out over more time, instead of doing longer sessions where it might be tempting to try and accomplish more than the horse can handle.
Phase 1: Spraying while grazing
This only lasted 2 days as I pretty quickly decided that I wanted to take a more structured approach where the reinforcer was contingent upon behavior. Still, I was glad I did this step as it gave me a baseline. Later, when he would ignore fly spray while grazing, I could see the difference in his behavior compared to the first few sessions.
Day 1: I led him over to the tall grass and let him eat for a minute or two. I had hand grazed him before in this location on several occasions. I let him eat and then sprayed the air around him and his legs. He backed up once, then went back to eating and kept eating while I did a few more sprays. I let him eat for a few more minutes and then put him away. He reacted to the spray by flinching and moving a bit, but he returned to eating immediately after and between each round of spraying.
Day 2: I repeated what I did on day 1, with similar results – he moved away when I started spraying but stopped and ate as soon as I was done. He was not moving a lot and didn’t seem anxious, but he’s not ignoring the spray either.
Phase 2: Spray, then graze – repeat a few times



Day 3: I brought him out and let him graze. Then, I started spraying his front legs. He moved around a little bit, so I asked him to stand, sprayed him, and then let him graze. I did this two times on each side. He clearly understood he had to wait for permission to graze (we had worked on this before) and I had better results making grazing contingent upon standing first, rather than trying to spray while he was grazing.
Day 4: I brought him out to the grass, asked him to stand, sprayed his front legs and then let him eat. I repeated that on the other side.
Day 5: It rained and we didn’t work on fly spray.
Day 6: I brought him out to the tall grass, asked him to stand, sprayed his front legs and let him eat. I walked around to the other side and sprayed his legs while he was eating. He stopped eating for a second but then continued.
Days 7 – 14: I started each session by asking him to stand and spraying a few times, then allowing him to eat. Then, I would spray him a few times while he was eating. Over the course of the week, I was able to spray new places (belly and hind legs) while he was eating. It seemed like we had gotten to a new place where he was aware of the fly spray, but would ignore it and continue eating. He didn’t move around in response to the fly spray except the first time I sprayed a new location.
Phase 3: Re-introducing fly spray in the grooming area


Day 15: After I sprayed him with fly spray while grazing, I took him back to the grooming stall and sprayed his front legs using picked grass as a reinforcer.
Day 16: I sprayed him while he was grazing.
Day 17: I sprayed him while he was grazing, then took him in the barn and sprayed him (front legs, hind legs) using picked grass as a reinforcer.
Day 18: I sprayed his front legs in the grooming area and reinforced him with picked grass.
Day 19: I sprayed him while he was grazing, then took him in the barn and sprayed him (front legs, hind legs, belly) using picked grass as a reinforcer.
Day 20: I sprayed his front and hind legs in the grooming area using picked grass as a reinforcer.
Day 21: I sprayed his front legs, hind legs and belly in the grooming area using picked grass as a reinforcer. Then I took him out and let him hand graze in the tall grass.
Days 22 – 29: I continued to spray him in both locations, trying to be a bit random about what we did where until I was sure he was equally comfortable in both places. I continued to use picked grass as a reinforcer.
Phase 4: Transition to other types of food reinforcers
Days 30 – 60: I started to vary the type of food reinforcer I offered. For most behaviors, I reinforce him with timothy pellets, but have also used carrots as high value reinforcers. This week, I experimented with offering different reinforcers, with the goal of slowly shifting him from picked grass to carrots or timothy pellets. I did not see any change in his behavior.
Days 61 – end of fly season: I eventually shifted him over to timothy pellets with an occasional carrot and that worked fine until the weather changed in the fall and we started to have colder nights. I noticed that if I sprayed him in the morning, he would flinch because the fly spray was cold.
Throughout this process, I felt like I was able to minimize his discomfort and the training progressed along nicely. Looking back now, it’s hard to say if the attempt at masking made any difference or not. I don’t usually like changing to a higher value reinforcer if a horse is uncomfortable with something, but I do feel like using grazing helped distract him from the physical sensation of the fly spray faster than if I had kept him in the grooming area. So, whether I used it or not, I do think that exploring the idea of masking was useful because it prompted me to think about different options for the type and presentation of the reinforcers.
A note about masking
I was introduced to the term “masking” in Karolina Westlund Friman’s Problem Solving course. She used it to describe a protocol where the animal is distracted by food reinforcers so that the trainer can do a medical or husbandry procedure.
This was not an unfamiliar idea to me, but the terminology was new, which might be why it caught my attention. I had already heard of (and used) a variety of strategies where food is used to distract an animal while something is done to them, but I had only used them when other options were not available, not as a first choice.
For example, when Aurora injured her leg and had to be cold hosed within a month of her arrival, my solution was to constantly feed her hay pellets while she was being hosed. At that point, I didn’t feel there was any benefit in trying to click and mark specific behavior, so I used food to distract her and encourage her to stay in one place.
In the end, I’m not sure that masking was different, or better, than any other strategy I could have used to help Madagascar over his anxiety about fly spray. But, it was an interesting experiment. In doing it, I learned a bit more about Madagascar and I did find myself thinking a little differently about about how to help horses cope with mildly aversive stimuli. I do think that most people (me included) tend to stick to what has worked in the past so it’s a good idea to try something different every now and then. The more ways we learn to train the same behavior, the more flexible and creative we can be with each individual.
Want to learn more about clicker training? My first book, Teaching Horses with Positive Reinforcement, is available in both Kindle and paperback. My second book, What Can I Teach My Horse?, is available in Kindle and PDF. I’ve put links to each book below:
Teaching Horses with Positive Reinforcement (Kindle version)
Teaching Horses with Positive Reinforcement (paperback version)
What Can I Teach My Horse? (Kindle version)
What Can I Teach My Horse? (PDF version)
Categories: Uncategorized
Tags: desensitizing, fly spray, grass as a reinforcer, masking