Our five year old Rex bunny has started to lose his fur in patches from between his ears and on his back. There are no other animals bugging him or causing this hair loss. It is in a location that he can't reach. We don't know what is causing this?
My husband (who bred and showed Mini-Rex Rabbits with 4H all through high school) says that he suspects fur mites with missing patches of fur between the ears, and no other rabbits. He was told at a conference that Vaseline is good to kill the mites followed by a bath in Dawn dish washing liquid to both get out the mites and remove the Vaseline from the fur. Neither will harm your rabbit, so it's worth a shot. The other possibility would be stress from the heat, if you're somewhere hot.
Please take you fur-baby to the Veterinarian for an exam. The Vet can check for mites, fleas or any other problem that is causing fur loss. Good luck