I find nothing in, say, the Christian faith that specifically excludes the
possibility that animals are conscious, intelligent, or self-aware.
There is the species chauvinism in genesis: 1:26
And God said, Let us make man in our image, after our likeness: and
let them have dominion over the fish of the sea, and over the fowl of
the air, and over the cattle, and over all the earth, and over every
creeping thing that creepeth upon the earth.
This is quite a different attitude that say taught by north American
religions. It leads to concepts such as "conquering nature", and the
use of human financial goals as the sole decision concern.
This is the source of the belief man is has a right to determine the
fate of all other species only considering himself. Other species are
man's chattels in this view.
The was the whole notion of soul in 19th century used to justify
slavery and the mistreatment of horses. There was no need to be kind.
They had no souls. I am not totally sure of this, but I gather they
felt horses and slaves were like machine. They could appear to
suffer, but since their was no soul inside, there was nothing to
actually suffer.
If the human soul animated the human body, I don't know what they
imagined animated the slave or horse, and why those too went through a
transformation at death when they gave up the ghost.