Jürgen Habermas
Habermas emanates in his ethical theory, which is described as discourse ethics, that norms (from which rights and duties result) have to be justified within practical discourses. This has to happen by all the participants of a practical discourse, being affected by a norm, convincing themselves that this norm is in everyone's homogeneous interest and therefore agreeing with it.
Habermas does not emanate animals appearing as fully valid discourse partners. In this respect the approach seems to be related to the Kantian one.
Habermas tries to avoid a strong anthropocentrism by enforcing a moral analogue responsibility of the human towards animals. This responsibility is based on that at least sophisticated animals can take part in our social interactions and experience us in the persona of the alter ego. Insofar we find in them an opponent which needs to be treated with care. With that it justifies an abeyance to fiduciary perception of its demands.
Habermas, Jürgen (1991): Erläuterungen zur Diskursethik. Frankfurt a.M.: Suhrkamp.