Not experienced in rabbits but am experienced in dogs and parrots. I have had a pup or two look similiar and the Dam wasn't stimulating them enough for them to urinate, I definately think that you may be on the right track. I used a warm wash cloth every 30 minutes or so until I got the pups to normal. I also increased the temps, I believe the pups were a winter litter and although inside, it was still perhaps not quite warm enough. That shouldn't be an issue though for you. I hope you can save them.