For introductory presentations see:

Huth, M. (2020): How to Recognize Animals‘ Vulnerability. Questioning the Orthodoxies of Moral Individualism and Relationalism in Animal Ethics. In: Animals 2020 10(2), 235. DOI: 10.3390/ani10020235  Online Version 

Zuolo, F. (2020): Views on the Moral Status of Animals. In: Zuolo, F. (ed.): Animals, Political Liberalism and Public Reason. Cham: Springer Nature, 129–181. Online Version 

For selected relationalist approaches see, among others:

Adams C. J./Donovan J. (1995): Animals and Women. Feminist Theoretical Explorations. Durham: Duke University Press. 

Midgley, M. (1983): Animals and Why They Matter. A Journey Around the Species Barrier. Athens: University of Georgia Press. 

Palmer, C. (2010): Animal Ethics in Context. New York: Columbia University Press. 

Palmer, C. (2011): The Moral Relevance of  the Distinction between Domesticated and Wild Animals. In: Tom L. Beauchamp & R. G. Freys (ed.), The Oxford Handbook of Animal Ethics. Oxford: Oxford University Press. 701-725.