Here's what I do with any that are afraid of a spray bottle. It has worked for several horses.
Put a halter and lead line (10 - 12') on your horse/pony. While holding the leadline (DO NOT TIE HIM UP) spray into the air AWAY from him. Let the horse move his feet. That is OK. When he stops moving, stop spraying and pet him. (But don't stop till he does). Let him rest for 60 seconds. Next, spray more in his direction. Again, let him move his feet, don't stop spraying until he stops moving. Next, spray closer or spray his legs. Keep getting closer &/or spraying more of him. This will take several days to get him used to the fly spray but once he's used to it he will just stand there while you help protect him from the flies.
- Do not spray aggressively. Stay very relaxed and calm.
- Don't stop until he does.
- Let him move his feet so he doesn't feel trapped.
- Don't push him too far. If he gets really scared spraying a certain place, go back to spraying the last place he was comfortable with.
- It's fine to start with water in the bottle, but remember, when you switch to fly spray you may have to work with him some more because of the different, stronger smell of the fly spray.
This has worked great for me. Good Luck!