As usual, once this building rolls around to you (it's on a slow roll-out as of this writing), you'll first need to place its base and then collect items to complete its construction. For this particular pet habitat, you'll need to collect ten each of Painted Wood pieces, Water Pumps and Fence Posts (the Fence Posts have been carried over from the Wildlife Habitat). You'll be given a single ingredient for free to start you out, but can earn the rest by asking your friends to send them to you, or by purchasing them for a single Farm Cash each. I haven't received any of these items by opening Special Delivery Boxes, so you may want to rule that option out for the time being.
Once constructed, your Farmville Animals Pet Run will be able to support the storage of up to 20 animals like those mentioned above. It should be noted that actual Puppies (that is, those that are fed both food and treats collected from friends) aren't allowed to be stored. You'll receive a free Himalayan Cat for completing each Pet Run on your land, and you can have as many as you'd like, so long as you build each separately.
Like the Wildlife Habitat before it, you'll be able to look inside the Pet Run once it's completed to see a complete list of each and every animal that is allowed to be stored inside, and once you actually place a corresponding animal into your Pet Run, its appearance inside will reflect that. Also, the list inside the Pet Run contains animals that may not be available, but we've been told some may make a comeback in the future.
In terms of breeding, you'll find one of two colors of Bassinets at random when you collect from the ready Habitat (you'll receive Feed otherwise). When collecting from your own Pet Run, your baby is guaranteed to turn into one of the animals you currently own inside the Pet Run, while the situation changes when claiming an animal from friends: A pink Bassinet signals a rare animal that would otherwise be available in the store for around 15 Farm Cash, while an orange Bassinet signals a common animal that would include past lonely animals, quest rewards and the like.
Farmville Animals All in all, this feature is basically identical to the Wildlife Habitat, save for the kinds of animals that can be stored. Building the structure is an incredibly familiar process by this point, so just keep chugging along, asking your friends for building ingredients, and you'll have your Pet Run ready for storage in no time!