"Since animals are the weakest sentient beings of all -- weaker than women and children -- animals will only be granted equality as free beings when enough free humans decide to award it to them, as happened with the liberation of black slaves. The idea of animal rights has existed for thousands of years, but now the idea of the right to liberation from bondage to humans; the understanding that animals are not ours to own, use, or derive pleasure from..."
Does this include your "companion" animals; pet dogs, cats, ferrets, birds, reptiles, rabbits, and insects, even though you love them and treat them well?
How can it not? We keep pets for our pleasure and some few of us ensure that our pets also experience pleasure; those are the "good" pet owners with "happy" pets, some who recently followed the big players in the pet welfare industry by reimaging their ownership from "owner" to "guardian". But one of the factors that entrenched the persistence of black slavery was "good slave owners" and "happy slaves". (19th century slave owners didn't have P.R. firms to advise them to re-label themselves slave guardians, but if they had, it may well have slowed the abolition of slavery.)
It was only when enough ordinary people understood that slavery is immoral -- in and of itself -- that black slavery was abolished; and only when enough people understand that owning any sentient being is immoral, for the same reason, will animal slavery be abolished.