Do animals have souls? It's a topic for debate but I believe they just might and more so than some humans. As a child I had health issues that prevented me getting out much & even now I still lead a somewhat isolated life. For this reason most of time was spent around animals from the chickens eating bugs to the deer strung up and butchered.
As a farmer, pet owner, and Hunter I've seen my share of animal deaths. When an animal expires it isn't like a plant dying but closer to a human; the body shuts down, the breathing stops and there is a visible light that goes forever dim in the eyes. There has to be something there for the Grim Reaper to harvest.
When you mistreat an animal it suffers trauma like a human. Some lash out others cower in corners as a pair of loving hands reach toward them. They are broken and have to heal. Surely there is something within them for that mark to be left on.
Perhaps they do not possess a soul like ours but rather one God made just for them but it is a soul nonetheless.