Hi Margarat,
My experience has been that smaller, more nervous dogs react poorly to reiki. The energy seems too much for them unless they are sick and truly desire it. Larger dogs like labs, especially, LOVE it! and are wonderful to work with. I do not have experience with shepards or Rottys but have heard they can be uneasy with reiki.
As with any dog, be mindful, be careful and when they "say" no, best to listen.
Also, if a dog is a bit uneasy but needs the reiki, you can beam the reiki to the animal from a safe distance in the room or from your own home.
I have also noticed that animals (the ones I have worked with anyway) require much less reiki than a human so plan on shortened sessions.
Hope this helps a bit:))
Tracey