Tara, a Straffordshire Bullterrier, lives on a farm near Amsterdam with quite a few miniature ponies. Anja Heppener, the animals' owner, said they love to clown around together, so she posted videos of their playtime.
Despite Heppener's joking title about Tara being "attacked," it's pretty clear these guys love each other. Just watch Tara roll over at :17.
If a free massage isn't a good foundation for an inter-species friendship, I don't know what is.