Animal Slavery

[Esquilax]

There are differences, of course; the animals don't have a concept of money, but we do reward them for their work with food and shelter and medical treatment, the kinds of things that are important to them that would be scarcer if they were in the wild. We have animal cruelty laws in place to prevent abuses, and in fact organizations in place that will take animals away from abusive owners.

I'm not so sure you can draw an equal connection between the human symbiosis with domesticated animals and slavery, here.