Oh man, that doesn’t look good. Unfortunately I don’t know much about sludgy pee, I just read this:

Bladder sludge (also called hypercalcinuria or hypercalciuria) is a thickening of the urine with calcium salts that never form into stones. Sludge may be comprised of any number of calcium salts, and does not flow as normal, liquid urine should. We are not sure why, but sludge does not form stones. It remains the consistency of chalk or fine sand, and is a white to gray color. Very thick sludge can have the consistency of toothpaste. When felt, this sludge can be smooth, have finely granular texture, or even have gritty texture. Sludge can form in the kidneys or ureters, but most sludge is noted in the bladder, and is suspected to have formed there.

At this time, it is not clear why some rabbits form stones, some form sludge, and why most rabbits develop neither stones nor sludge. Most likely, it is a combination of factors that contribute to this pathology. These factors are listed and discussed below. However, I would first like to comment on the rabbit’s peculiar physiology with respect to calcium metabolism.

it’s from http://www.rabbit.org/health/urolith.html

Maybe one of your buns has a problem with the bladder or has too much calcium in the diet? I really am not sure. Hopefully someone more experienced can help.

Unfortunately I am not experienced with sludge, but my common sense suggests that you give them clean, fresh water and hay, with little else overnight until you can contact your vet. My thinking is to gently flush them out with ease, lots of hydration, and not challenge what’s going on with any other food that may be more difficult. If one of them shows any sign of behavioral change, you may be able to identify who it’s from. You could try separating them for the night with separate litter boxes, so you can clearly see who does what. Have an emergency vet’s number handy in case you need to act more quickly, but otherwise, you might be able to get the right bunny to the vet tomorrow.

It doesn’t really look like sludge to me. You would have other symptoms usually with sludge too – it’s hard to pass. Many times you will see your rabbit frequently try to urinate and/or have a wet bottom.

I’ve seen sludge like that before. Both my buns had sludge until I drastically reduced their pellets and increased their water intake.

Try to watch them when they go to the bathroom. They’ll often posture and jerk their rear end up when they pee because it hurts, so you might be able to figure out who made that.

Sorry to hear of your worries, Grumpbun. My male rabbit, BunBun, had some bladder sludge identified on an Xray- one vet called it “calcified urine”, the other said “bladder sludge”. I have noticed him sometimes posturing and sticking his bum up in the air like Peepi&warri just mentioned, but never realized what it was from . I even took BunBun to the vet for that behavior, thinking he had a UTI. Of course the vet (not my usual- and NOT my favorite) said it was probably a UTI and prescribed him antibiotics.
Anyway, it seems to come and go with BunBun, his odd litterbox behavior. I’m gonna start keeping a diary of what food he eats when he does it.. maybe it’s connected. Keeping them extra hydrated is helpful- only thing is I don’t know about your buns, but mine never seem to drink! I eve got BunBun a salf lick again, cuz he used to lick it, drink water, then repeat several times. The only other alternative would be syringe feeding, but it depends on how docile the bun is.
Come to think of it (and it may be unrelated), the two episodes of tummy trouble Bunbun had both coincided with some VERY chalky urine being found on his favorite chair- looked like dried milk and was really thick. I will search for more info online, in case Oxo does have bladder sludge too. I need to find out more about it anyway, now that I realise that all the posturing BunBun sometimes does is related to bladder sludge.
Good luck at the vet’s !

I think the mexocam is the painkiller and the baytril is the antibiotic.

I’ve lived with many rabbits with bladder sludge and it is a frustrating condition. Flushing will help temporarily but it is most likely always going to be a condition with your rabbit.

The vet can also show you how to express his bladder and that can help disperse the sludge out of his bladder.

One of our vets gave us a hint about hydration. He told us to wash any greens bunny gets just before we give them to him so they are really wet. We make sure there is a little water in the bottom of the dish of greens. It may be a little bit messy but it helps with water intake.

Jack does get that but he is now on a special diet that helps keep him hydrated – no pellets, all greens and hay, and the unsweetened apple juice water mix (which he does drink alot of and that has really helped), however, sometimes, for whatever reason, when he decides to drink less, or his body still produces sludge, we give him sub-q fluids. We used to do it every other day, and then 2 times a week, and now we do it about once a week. Jack also does not have a messy bottom, so his sludge problem may be lighter than others. However, he has developed a stone in the past, so I keep a very close eye on his hydration level. For more details about his vet recommended diet check out. https://binkybunny.com/BUNNYINF…fault.aspx

I just had a bunny get over a small infection in the bladder with sludge. Since she’s never had a calcium rich diet, we don’t believe it caused by that but just more of something some bunnies are more prone to then others. Hereditary maybe.
A severe case i had never got infections or crystals, it was more caused by her lack of mobility (she was partially paralyzed) and probably that fact before i took her in she had a terrible diet.
I think making sure the rabbit is drinking enough regularly, and is not given to many things that are high in calcium are a reasonable preventative. My own thought or suggestion is if it’s not a re-occuring thing and the rabbit is not having issues with crystals/stones forming flushing the bladder or regular Sub-Q fluids should not be necessary.

Just a note, rabbits urine is already high in calcium normally, this may be something to read up on or get information from a Rabbit Savvy Vet on. After I talked it over and was explained how calcium and rabbit work I found I was much less stressed about the sitiation.

Speedy recovery to your little guy