I'm not entirely sure what energizes this shift. It could be that Westerners love their pets more than ever before. Or maybe with the emergence of the "Internet of Things" we are also seeing greater attention to things in general.
It is certainly the case that phenomenology opens space for considering not just that things are (ontology), but how they present themselves (phenomenology). So, you get a fascinating little book like Ian Bogost's Alien Phenomenology, or What It's Like to Be a Thing (Posthumanities), which explores in very accessible prose the emerging field of Object-Oriented Ontology.
"That things are is not a matter of debate. What it means that something in particular is for another thing that is: this is the question that interests me" (39).
Bogost's book is one example of the shift towards things in philosophy and metaphysics.
The most recent book on animals and theology is Elizabeth Johnson's Ask the Beasts: Darwin and the God of Love.
I have a special love of Johnson's work, and even did aninterview with her for Word & World back in the 1990s. Her book is one outstanding example of the emerging field of eco-theology.
Johnson believes, with many others, that if a primary doctrine of the faith is the doctrine of creation, then all creation matters as part of what we examine when we talk about God, the creator. One of the more curious parts of creation are our fellow animal creatures.
Below I provide links and a few comments for other books in these emerging fields. I'm fascinated by how many there are, and how deeply and carefully these theologians and philosophers are thinking.
On Animals: Volume I: Systematic Theology
Religion, Politics, and the Earth: The New Materialism (Radical Theologies), by Clayton Crockett, a fellow Arkansan
Speculative Grace: Bruno Latour and Object-Oriented Theology (Perspectives in Continental Philosophy)