There is a movie I cannot get out of my head. Most likely from the 70s or 80s. In color.
An older man looks after animals. What is interesting is he makes a big deal about training the animals not to exit the cage because the door will shock them (or has some kind of force field.)
The part I remember best is the man ends up capturing or kidnapping a man and woman and cages them. They have a small door to the outside world but they don’t know if the door is turned on or not. At some point they have a puppy, or perhaps they had it from the beginning, but one of them or maybe both of them decides to toss the puppy through the door to see if it’s safe. It kills the puppy.
I don’t remedy how they escape, but I remember they somehow got out and killed the man. The twist ending, however, is once they get home they realize their house was rigged to be their new cage, but now they killed the only man who could release them and they will be trapped forever and probably starve to death.