My vet recommended a month treatment of GastroGard for one of my horses. Even though it's very expensive, I'm just going to get what she recommended because I don't want to take a chance with something compounded or another product and then wonder if I should have just done what the vet said. My question is, has anyone had a problem with a horse eating it? I would hate to spend all that money and then have a problem getting it into him. If it matters, he's a real easy keeper and barely eats a handful of grain. Thanks in advance!

It comes in the same type tube as Zimectrin dewormer, pretty hard for them to spit out. No, it doesn't taste good. There's a rebate for it if you google "Gastrogard rebate".

I use the NexGen omeprazole. No complaints here. It's great.

Thanks for that tidbit. 

It is a paste in a tube, so they aren't eating it. 

I am using a powder omeprozalene, I believe it is compounded, it is a prescription from the vet - smells amazing!!  I haven't tasted it, but my gelding is not complaining about it, according to the trainer.  

Since it has to go in his mouth, I was concerned about him getting resistant if it tastes bad since I will be giving it to him for 28 days.

I just treated my mare this summer and had no issues. Now my vet recommends giving 1/4 tube 3 days before an event, the day of and 3 days after. I can give it to her without even putting a halter on her. When giving the full tube I would recommend giving part of the tube and then letting them swallow and then giving the rest. I think sometimes we jam a whole tube  down and that's what creates the issue vs the taste.