What exactly IS the soul in this context anyway? If it means that which makes the nature of a person's individual character, his or her ability to love, and hate, and rejoice, and grieve I think it would be difficult to deny that animals did have a soul too.
If instead it is what makes up the human consciousness which enables us for example to plan ahead and think about the consequences of our actions on a higher level than animals in general (though there ARE cases where animals, primates in particular, have been acting in a way that DOES suggest a certain degree of consciousness) things are getting more tricky.
But is the soul something so purely "intellectual" as consciousness?
What is the soul?