I had another little session with Percy and the syringe yesterday afternoon. I took some warm water out and sucked some up into the syringe. Then I let him bite the end of it a couple times for a Click/Treat and then when he took it the next time, I squirted some of the water in his mouth. It did surprise him but I C/T'd and tried again. He wasn't too sure but did it again with the same response. hmmmm. I need to work on that part even more slowly. I stopped there so I could spend some time coming up with more baby steps.
This morning, I wore a different coat to the barn so I didn't have the syringe in my pocket. This was probably a good thing because I wasn't sure if he'd want to try it again and it prevented me from trying it! I went hunting in the tack room for a suitable substitute (I wanted a pen with a cap but had removed them all in early winter so they didn't freeze and break). I did find a little plastic "pin" for an electric fence gate that was about the same diameter as the tip of the syringe. I thought it would be a good imitation since it was plastic and a little pokey.
I think the term for what I am doing here is called generalization. I don't want him to think that this "game" is about standing in a particular place, using a particular tool, or inserting something in his mouth in a particular way. And animals do look at things that way. A willingness to walk into one horse trailer does not necessarily carry over to comfort walking into a different trailer. So while I am avoiding touching his wound so that I don't hurt or discourage him, I do want to put various things in his mouth, in various ways (different parts of his lips) and with different results. I hope this will make him less hesitant in the future for any necessary procedures involving his mouth: worming, checking teeth, bits, etc.
He was game to give the little plastic pin a try and pretty soon was happily grabbing hold of it with his front teeth for C/Ts. Somehow I needed to get the ability to stick something in the side of his mouth. I went back to steadying his nose with one hand and then began brushing the corner of his lips with the pin. That was OK too. Then I thought I should see if I could get him to target the corner of his mouth to the pin. This would put the action in his hands, rather than just asking him to tolerate my actions. I held the pin right next to the corner of his mouth so his smallest movement had his lips bump the pin. I did this several more times until I thought he really might be doing it on purpose rather than just bumping it accidentally and then I gave him a jackpot of a handful of pellets and stopped there.