Depends totally on the individual dogs temprament. I say go to your local shelter and see what you can find there.
Other wise I say Dalmation.
Love thos spots :P
But seriously they were used in the old days with horses. They accompanied the horses that pulled the carrages for firemen to put out fires. So in part were bred to be around them. Altho that purpose has totally gone now so don't know how many of them would carry the horse friendly trait any more.
So again depends totally on individual dog.
But I so want one 8)