I would have him assessed by a rabbit-experienced exotic veterinarian for what may be an underlying cause. Rabbits should not be urinating on themselves, so whether it is a bladder and/or movement issue, that is something a veterinarian should be able to help you with.

A picture of your litterbox set-up would also be helpful. Our forum is right now a bit finnicky with adding pictures, so if you’re unable to add it, you can upload your photo somewhere and then link it here. A spacious and well set-up litterbox is also important to prevent urine staining.

Something is wrong if a bun’s butt is wet after he pees. Wet fur will harm the skin and can cause urine scald and/or offer an ideal environment for skin fungus or bacteria. I’m pretty sure you know all this, so I’m only mentioning it, it could be helpful for other readers of this thread.

You can give a butt bath, and you can give him a sanitary shave. A vet tech can do a shave and show you how, so you can maintain the fur short. It’s a bit difficult to do it yourself, since rabbit skin is so delicate. Once the shave is done, you can put barrier creme (diaper rash cream, vaseline, bees wax salve etc) on the skin, to protect it from moisture.

A not uncommon root cause of incontinence in rabbits where the symptoms dont fit a UTI, is e cuniculi infection. E cuniculi is an intracellular parasite that many buns carry asymptomatically. They can suddenly start to show symptoms, and iys not fully understood why. Ec typically affects the central nervous system and/or the kidneys. It is treatable with fenbendazole (Panacur) for 28 days.

Yes, definitely not normal. Something is wrong. If it isn’t a litter box issue, then it could be a UTI or EC-related incontinence as Bam said. I would have him assessed by a vet. In the meantime, yes, you do a sanitary shave to keep things drier back there.