There's not an obsession with robotic animals in the book, it's an obsession with animals and keeping them as part of the new religion, Mercerism, and its hyper-focus on empathy, and consequently displays of empathy. Caring for an animal is part of that. The robotic animals are not meant to be recognized as robotic, they're surrogates so people can still display their care of an animal and demonstrate empathy even if they can't afford a real one. Real animals being rarer and more expensive, and of course dying much more easily than a machine, as happened to Deckard's prior to the events of the novel.

> people can still display their care of an animal and demonstrate empathy

It's neat that the adaptation for Children of Men also did this, even though it's very much in the background.

The obsession with animals is also a mark of humanity - lack of compassion for animals is part of the anti-replicant test. It's also a mark of the current neuroses of Humanity: making mechanical imitations of life, including human life.

>robotic animals that's not in the movie at all

Although I haven't played the game or read the book, the movie features a robotic snake, and there's dialogue about real snakes being very expensive. It seems reasonable that this would apply to other animals too.

The animals are mentioned briefly in the film, but in the book, they are a major plot point. Decker mostly wants the money because he wants to buy a real animal.

Isn’t the owl in the movie too?

Many. Fantasy, 1920s explorers, egyptian, we've had everything :)