In the most recent update, FarmVille released new Miniature Horses and Mini-foals and once you breed them you'll get a variety of new ponies to add to your farm. Below, see official FarmVille pics of the Mini Foal, Mini Stallion Foal, Mini Cream Horse, and Mini Cream Foal.
Please note the Mini Cream Horse and Foal can only be obtained from stables and nursery barns. You can get a side-by-side comparison of mini-horses and foals in the image below
How many Miniature Horses and Foal do you have so far?