Does anyone know what the pimple like things are that my great dane gets on his muzzle?

Most likely you will need to ask the vet. Sounds like something that can go to the next regular visit.

It is nothing to worry about. labman's right. At your next visit, speak to the vet about it. It could be the result of any number of things. If you give your dog large objects to chew on, like a kong, the rubbing against the muzzle can create irritation that causes pimples. Sometimes dogs, like people, are sensitive to certain things in the environment and it causes a breakout. The best thing to do is to speak with the vet about it.