Animals have souls too, and they may have their own lessons to learn.  The souls may not be as highly individuated as those of humans, perhaps their family or group soul mingles more.  But this distinction is not an important one.

Frequently animals or pets who have died greet us on the other side.  Animals are here to teach many lessons.  One of the lessons is unconditional love.  Animals will sacrifice themselves for their owners oftentimes.  People tend not to do that for each other.

Often people want to know if their pets will return to them.  I have known this to happen.

Many people have also asked if animals reincarnate as other species of animals, and I think, yes, there is a kind of progression through many different stages.  We can change our species and kingdom if we choose to, for that may offer us a new avenue for learning.  We can explore animal consciousness  or plant consciousness, or even the consciousness of the clouds.  Why should we ever put any limits on our awareness, on our soul?  Energy is energy.  Consciousness is consciousness.  And all sentient beings have an existence and have a soul and can therefore reincarnate.