your area is completely without birds of prey? that’s surprising. and you can’t count on predators behaving around prey. your dog is also a predator. he may be trained to leave the rabbit alone, but that doesn’t mean you should leave them together unsupervised.
is your rabbit not used to being handled? are you rough when putting him in the cage?
Likely stress
Make sure you’re giving established kitty attention
Supervise play
Perhaps a pheromone collar or feliway