Rabbit poop is tinged with blue

[TirithMinas]

I've been keeping my rabbit in his hutch in the garage to keep him out of the cold outside, though I let him run around in his own room in the house everyday. I've noticed that some of his poop would have a blue covering in his litterbox, and I have no idea what it is. I tried to look ig up but I have not found anything. My only guess is mold, and I would attach a photo, but you can hardly see it in any picture. Help!

 

[Madelyn L.]

I would take your rabbit to the vet immediately. Diseases can be spread from the outdoors to your rabbit, so you need to get your bun checked out quickly! I hope he gets better.

 

[Diane R]

It may be urine? Urine can turn blue after eating certain plants.

 

[2Bunns]

Is there any sort of bedding or litter which could account for it? Try placing a small bit of bedding and a small bit of litter in 2 separate glasses of water and leave for a few hours then see what colour the water goes. I found what first i thought was blood in their water bowl!!!!!!!!!! Panic panic panic!!!!! Was one of the breakfast mix they put in there... god only knows why but they do it alot, drop the red biscuits in their water. Im sure they watch me from afar and laugh their tiny tails off at my panic.