I have to admit I cheat and when my horse teeth are done 6 monthly she is sedated so I worm her then. I then struggle to worm orally for the other twice a year persistence usually pays off but it can take a while. Have you tried twitching then worming?
Have you thought about one of those worming gadgets.It is a headpiece with a bit like thing.You put it on the horse then the bit is like a hollow tube.Like this!.
My daughters pony is absolute nightmare for worming, we bought one of those worming gagdets, its like a hollow plastic bit with a headpiece on, it was brilliant pony didnt have a clue she was being wormed, only drawback not all the different types of worming syringes actually fit into the plastic bit which fits into the mouth so it is abit of trial and error, it seems the really thin skinny syringes fit best. Hope that helps.
I bought one of those easywormers things, but never used it and it is still looking for a home. Instead, I used to save a worming syringe and I would fill it with apple sauce and give this to the horse for several days before worming. On the day of worming, I put apple sauce on the outside of the tube, and the horse usually takes it. I then give a further day or two of apple sauce after worming. Has always worked for me, worth a try
We brought one of those for my brothers pony, who was really bad all he would do was rear and it was impossible to get it in and im normally pretty good!!,
the problem we had with the easy wormer thingy was the bit you attach it to was very near the mouth so he soon realised and then we could never get it connected again!
My friend's horse won't touch anything that smells odd. Or anything that may be suspicious (a horse never knows when he or she may be poisoned by these humans, you know!). We tried everything but the only way we can get anything down her is to syringe it into the mouth, and stand there with her head on your shoulder, massaging her throat. She always does a fake swallow first so I wait for two swallows then let her head go. Any sign of spitting and the head is up again! She then has to be turned out (dinner before working or she'll not eat it) and will stand there looking at the grass as if it's poisonous (of course everything then smells of wormer so she literally won't open her mouth for about 12 hours). She gets over herself when she gets hungry! I do this for my horse too, she's not too bad but is a bit suspicious and so will spit rather than swallow! At least Crackers (friend's horse) is only a little dainty Anglo Arab, my whacking great big middleweight ID X is a bit heavy to hold her head in the air for long!
I do like the apple sauce idea though, very cunning!
i used to have a huge problem with one mare and would take ages to get her wormed but the last time i held her top lip gently but firmly and she was easy as anything, no messing around it was great and she was a lot happier too.all our others are brill to worm even the foals come up for their regular worming, they do prefer the apple flavour one though lol