Yes, I know people who use it for pain with their dogs and it works with some / not as much with others just like humans.
It is pretty harmless but I would consult the Master trainer for a dosage before I would state how much to give. He would know as he used it with his Malinois.
Another question is how old is the dog and what brought the anxiety on? I had dogs who were abused and we rescued them and slowly I desensitized them to their fears. One was scared of noises, cars, people, etc. So I would only feed him in a parking lot. Short little walks around with people, carts, cars, etc. and then he gets his food. At first he would not eat after. In time, he would eat after and we could spend an hour talking to people and he wasn't shaking and didn't have his tail tucked. Afterwards, I carried the food with me and just for the safety of the strangers I muzzled him and asked people to feed him and explained what I was doing. It took a long time but he turned out to be a wonderful part of my family. If only I could have a few minutes with the cock sucker who beat him and broker his ribs and then left him on the side of the road or at least that is the assumption as he feared men much more than women and vets confirmed via x-rays the broken ribs that healed look like he was hit with a bat and not crushed by a car.
What are the symptoms of anxiety? I can shut up now as you only asked if CBD can be used lol.