I'm sorry. I am going to have to pick a bone with you.
You RESCUE (verb form). You don't adopt rescue (adjective) animals. You RESCUE (verb) animals that we adopt.
We adopt a RESCUE PET FROM YOU or some other rescuer.
It is true that those of us who adopt rescue animals did not do the verb form rescue. But we do adopt rescue (adjective) animals rescued by someone else.
So I'm not quite sure what the beef is. You are the VERB (the action) we adopt the animals youi and others have rescued.
Therfore we adopt rescue animals. If you want to get sticky about it, youi can say we adopt rescueD animals. But the adjective still applies.
There is a huge difference between adopting an animal from a breeder or pet store and adopting an animal you rescuers rescued.
But the adjective(s) "rescue" and "rescued" say with the animal.
Sorry to be so picyune, but then you also were being picyune. I grant you the verb. You grant me the adjective. It is grammatically correct. And I gotta tell ya, while you are an expert on rescuing animals, I am an expert on language.