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Rabbits/How to know when it is true Megacolon


Hi Dana,

a few months back we took a bunny into our rescue that came from a house with an abundance of birds and was having respiratory issues because of it. He recovered quickly from his respiratory ailment at the hospital where he stayed for a few months while waiting to be adopted. Eventually our rescue took him since he could no longer stay at the hospital. Since then we have noticed that he drinks incredible amounts of water, far in excess of what's normal for a 5.5 lb bunny (up to over 1000 ml a day#. Xray showed fluid accumulation in his abdomen during one of his vet visits. Blood tests showed high ALT but otherwise nothing out of the ordinary. Subsequent ultrasound showed nothing abnormal in his abdominal cavity either. For one day he was put on limited water to see whether his body would be able to concentrate the urine, and it did just fine. So the vet thinks that his drinking might be psychological, possibly due to boredom. So I took him into my home two days ago to see whether a little more attention would make a difference.

I instantly noticed his giant egg shaped poops and it occurred to me that Megacolon might be the root of the problem. A few things to support that theory:
1. He has the typical Chalie Chaplin coloring #white with black rings around his eyes, a black mustache, black ears and a thick spotted line down his back#,
2. he is intermittendly leaking fluids from his anus
3. Mixed with his giant egg shaped poops are a few small, mishapen fecals #haven't really seen any cecals yet#
4. A friend of mine said that she went through a phase of low sodium in her body which made her extremely thirsty. I came across an article that talked about low absorption rates of sodium in Megacolon bunnies. So that would fit his excessive drinking.
5. While he was still in his previous foster home, he did have a short period of lethargy, though in the 6 months we've had him we haven't seen any true GI episodes #which might be possibly be prevented by his excessive water intake)
6. He is somewhere between 3-4 years old, at which point I understand Megacolon symptoms usually start.

So to make a long story short, how does one know for sure whether a bunny is suffering from Megacolon. My friend who fostered him previously does not believe that he is suffering from Megacolon because his poops aren't totally mushy. However from whatever pictures I could find online it doesn't seem as if in order to qualify for Megacolon poops really need to look like mushy cow piles.

I'd appreciate any insight you might be able to offer. There really doesn't seem to be too much reliable information out there. My Rabbit Medice books don't even mention the condition.


Dear Astrid,

There is no way to ascertain with 100% certainty that a bunny is afflicted with the faulty intestinal tract innervation that results in what some call "megacolon" and other call "cow poop syndrome".  But it sounds as if your bunny fits the description.  Each individual can be affected to a greater or lesser degree, and the severity of the condition is often--not always--correlated with the degree of pigmentation.  Rabbits with less dark pigment are often the most severely affected.

The poops of a "cowpoop" bunny are not mushy.  Rather, they tend to be unusually large, often misshapen (oval or lumpy), and hard/rubbery rather than friable.

I think it's a reasonable idea that your bunny is drinking so much in response to being thirsty because of a sodium-ion channel problem he's having.  This would help explain why the GI tract does not properly hydrate fecal contents in the gut and, hence, produces those nasty, big poops.

If the kidneys are concentrating waste just fine, I would not worry about that.  It's possible that the bunny is managing his GI condition this way, and it's the only thing he can do.  So just keep providing plenty of fresh, clean water and hope he can keep the progression of the GI problems at bay for as long as possible.

High ALT signifies only that there has been an insult to the liver (or possibly muscle), and it could be due to any number of things, from inflammation, infection, parasite infection (coccidiosis?) or transient toxic reaction to something.  If a followup blood test shows the same thing, the vet might want to pursue further diagnostics.  But it's not necessarily related to the GI tract disorder.

Not sure how much help this is, but I hope your bun does well.  He's lucky to have found you!



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Dana Krempels, Ph.D.


I've lived with companion rabbits for more than 35 years, and consider them members of my family. I can answer any questions about the biology and health of rabbits, from the commonplace to the unusual. But please note:

RULE #1:

Find a rabbit vet at for immediate help, and don't risk your bunny's life by spending time asking questions online! If you can't get in touch with your vet, read these Emergency Sick Bunny Instructions.

If you have found a wild baby rabbit, please read these EMERGENCY INSTRUCTIONS FOR WILD BABY RABBITS and then use this link to FIND A LOCAL WILDLIFE REHABILITATOR who can give you the right advice.

RULE #2:
Help me help you! Please make your subject line informative if you have an urgent question. then LET ME KNOW IN THE SUBJECT LINE so I can give your question highest priority over non-urgent questions. If you don't do this, then I can't guarantee timely assistance!

For all the best, most accurate rabbit health, care and behavior information, visit The House Rabbit Society.


I have been rescuing and rehabilitating domestic and wild rabbits for about 30 years. I have written articles for many rabbit rescue publications, as well as for the veterinary journal, Exotic DVM. I own EtherBun, the internet's largest listserve dedicated to health, care, and behavior of domestic rabbits.

Houserabbit Adoption, Rescue, and Education, Inc. (H.A.R.E., Inc.) president National House Rabbit Society (Board member)

Exotic DVM
Warren Peace (Journal of the House Rabbit Society of Miami)
Various newsletters of the House Rabbit Society, nationwide

Ph.D - Biology
B.S. - Biology
B.A. - English

Awards and Honors
Lightspan Academic Excellence Award for web site on rabbit health and biology

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