New information has come to light regarding the beast nicknamed "space horse" as seen in the image above from the set of The Last Jedi.
In Star Wars: The Last Jedi I have learned that the horse we used to call “The Space Horse” is actually called a “falthier.” They’re race horses. As we’ve noted previously, Canto Bight has gambling and we used to call it “the casino planet.” Well, the falthiers are high-dollar “race horses” on the world. The beige/brown falthiers were glimpsed last summer during filming on location in Dubrovnik. The head of the horse is sort of like a cross between a tauntaun and and the luck dragon from The Neverending Story.
If you're up for even more spoilers, MSW goes into further detail about the scene from the photo above right here