Play stands as one of the most natural and inherent behavior among the majority of living species, specifically humans and animals. Human play has evolved significantly over the years, and so have done the artifacts which allow us to play: from children playing tag games without any tools other than their bodies, to modern videogames using haptic and wearable devices to augment the playful experience. However, this ludic revolution has not been the same for the humans' closest companions, our pets. Recently, a new discipline inside the Human Computer Interaction (HCI) community, called Animal Computer Interaction (ACI), has focused its attention on improving animals' welfare using technology. Several works in the ACI field rely on playful interfaces to mediate this digital communication between animals and humans. Until now, the development of these interfaces only comprises a single goal or activity, and its adaptation to the animals' needs requires the developers' intervention. This work analyzes the existing approaches, proposing a more generic and autonomous system aimed at addressing several aspects of animal welfare at a time: Intelligent Playful Environments for Animals. The great potential of these systems is discussed, explaining how incorporating intelligent capabilities within playful environments could allow learning from the animals' behavior and automatically adapt the game to the animals' needs and preferences. The engaging playful activities created with these systems could serve different purposes and eventually improve animals' quality of life.