Sarah Fernandezlopez says:

I have not heard of a preference for all dogs, I’ve just heard that dogs often do have a preference. Here’s an interesting article with some research that shows that being “right-pawed” or “left-pawed” is much more evenly distributed.

https://www.psychologytoday.com/us/blog/canine-corner/201307/dogs-left-paw-preferences-may-be-different-emotionally