Sorry if this is a bit too conceptual, but it's necessary I think.
Bob Torres writes, "The recognition that animals have interests that deserve to be respected," is what is meant by the notion of (moral) "rights." I agree with his argument. However, the conceptual basis for why an interest "deserves to be respected" should be noted.
I previously wrote a post about the importance of sentience, which is, I think, fundamental to this discourse of moral "rights":
If an individual is the kind of being capable of having any interests at all (i.e., sentient) then that being has intinsic or inherent worth, which is the "minimal criterion necessary to be regarded as a member of the moral communiy" (Gary Francione). Inherent worth differs in kind from external worth, or instrumental worth given to an object by a person: a piece of gold, for example, has no worth independent of our valuation of it; our valuation gives this object worth because it serves as a resource to us. Property is an example of an object with worth only as a resource to others.
Now, in order for some individuals to be protected against being treated as mere things, all members of the moral community must be regarded as being equal possessors of inherent moral worth. Moral worth works this way because inequalities in the inherent worth of the individual is irrational: If I can validly claim to have intrinsic value because I am a particular type of individual, then all other individuals like me (with that particular characteristic) have this intrinsic value as well, or else I can't have a valid claim either - which doesn't make any sense.
Speciesism, then, would put all non-human animals into the category of property (i.e., as possessors of external worth only). The "rights view" rejects this, arguing instead that if an animal is sentient than she is reasonably viewed as having interests, and interests ought to be respected in cases where morally relevant differences are absent as a matter of strict justice. For the rights view, then, as the only morally relevant characteristic is sentience, as a matter of strict justice human animals and non-human animals alike ought to have their interests respected.
Gary Francione offers an argument in favor of legal rights (as derived from the above stated moral argument). Francione believes that rights are a "special way of protecting an interest." He invokes rights to challenge the property status of non-human animals because until all sentient beings' interests are given equal consideration, as equal possessors of inherent value (as opposed to chattel slaves, for example), ending the exploitation of non-human animals is an impossible goal to achieve: no matter how much a piece of property is enjoyed or appreciated by its owner, even the most basic interests of that piece of property (e.g., to avoid pain, in the case of our animal property) will always be trumped by its owners' most trivial desires or preferences (e.g., "I like the taste of flesh").
One final note, rights protect those interests natural to the individual whose interests are being protected. If a being is sentient, not experiencing pain or being free to continue life for example, can reasonably be called natural to all species of animals, which ought to be protected by basic rights. Basic rights are those substantive rights that all other formal rights are derived from, or on which they find their foundation: without a basic right to be treated as an end in and of myself in a community of ends, for example, my "right to free speech" is not substantive because I am already unequal to all those people I am speaking too; this means I might as well shut the hell up because I don't count anyway!
So, it would be absurd to speak of a dog's or a human infant's "right to vote." However, it would be equally as absurd to speak of a dog's or a human infant's inability to subjectively experience pain; thus a basic right to be free from pain, for example, should be extended to both the dog and the human infant. As another example, no reasonable person could argue that both of these individuals do not have an interest in continuing to live their own lives as sentient beings; living, of course, allows for the fulfillment of those actions and things that naturally bring the individual happiness or enjoyment. A basic right ought to protect this interest as well.
Rights, then, have a fundamental moral foundation as well as a necessary legal application.

