Should people really find lab testing of soon to be euthanized animals that repugnant?

Somewhere over the last day or so seeking a question worthy to answer, I read a comment about unwanted pets ending up in lab test via Craigslist. That made me think why would, or should that be repugnant, or seen that way? The animal is a dead dog walking (or cat). Who is to say that particular condemned pooch or kitty would not be the animal a breakthrough drug or something else beneficial to humans came by? That would make the demise of the animal at lease be worth something where before its death was because there was no place of it. If people are to get so choked about the animal or its suffering, maybe they should act to adopt more. If the animal is going to die anyhow, and no one owns or wants it, why not allow the inevitable death to assist or help humans in some way?