Chapotraphouse

Please read my full comment before replying. I specifically said:

For the record, I don't necessarily disagree with this on principle

by which I was referring to applying eugenics to animals. I simply draw a distinction between getting rid of genetic diseases and committing genocide.

the abolitionist position is to selflessly care for these animals until they are fazed out

And what does "fazed out" entail? I can see that you care for individual animal lives, but I view letting the species die out as morally equivalent to killing them, while it seems that you attach no moral weight to the existence of the species itself at all. Which is fine, but if you're going to argue that species in themselves don't have a right to exist then argue that point, don't dance around it like you're currently doing.

Letting a genetic line fade by refusing forcible breeding

This is a shift of the goalposts. Earlier you specifically mentioned mass sterilization to prevent feral animals from continuing to breed, justifying it by the bad conditions they live in rather than advocating for an improvement of those conditions.

at the complete cost of their autonomy

This is what I mean when I said you have succumbed to "animal ownership realism." It's a deliberate invocation of the phrase "capitalist realism", which refers to the tendency of people under capitalism to have difficulty imagining non-capitalist systems. You are having difficulty imagining a paradigm where animals simultaneously have autonomy and are cared for by the people they live around/with. I want to imagine it is possible to have a world where animals live with humans not as property.