
Pony Play is probably the most common of all animal role-playing games. One human plays the pony and the other plays the master or mistress. There are actually entire events where BDSMers get together to dress up as ponies and have actual competitions with cantering, showmanship, training, and hoofing. Wow!
Puppy Play is, obviously, when one human acts like a dog. The master will train the dog. One friend of mine had a boyfriend interested in puppy play. Here was the scene he described to her:
I want to eat dinner while you kneel at my feet with a collar and a lead [British word for "leash"]. I'll eat my whole dinner, but you can't have any. Then I'll take the lead and lead you upstairs. We'll have sex doggie-style, and you have to yelp like a puppy.
Kitt

Many BDSM stores (although none I'd recommend) sell outfits and gear for pony, puppy, and kitty play. There are collars, leashes, riding tack, mouth bits, blinders, saddles, bridles, and stirrups. Riding crops and trainers' outfits are available for the Mistress. You can buy bridles and reigns shaped for either the head, breasts, or body. There ar

If you are interested in this fetish, you can buy the gear if that makes you happy, but you

Whether you find this amusing or kinky, it doesn't hurt to try. You can just play the role nonsexually to see how it feels. Many Doms may like the feeling of power, but not need the role to become sexual. Of course, it can become sexual: this type of play is called bestiality play. I must stress that BDSM does not condone actual bestiality, but only consenual human play where one person is pretending to rape an animal.
And if you try this fetish out, please, let me know how it goes! :)