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Rabbits/My neutered male rabbit is acting hormonal and spraying everywhere.


Hello Dana, We have had our two male house rabbits (brothers) since they were 3 months old. They're now 5. We had them neutered at 1 year old and that seemed to calm them down a bit. They've been pretty much litter trained since then with the old incident of weeing or pooing somewhere they shouldn't. One rabbit has always been the dominant one and humps his borther now and again. But about one month ago, we noticed the less dominant one was chasing his brother around A LOT trying to hump him. This has got increasingly worse with it happening every few minutes while we are around. In the last couple of weeks he has also been pooing all over the house and weeing too. He also seems very excitable when we are around. They have always done a happy grunty sound and run around in circles when they're happy. i.e. about to get treats etc but he's doing it every time we are there for seemingly no reason. We have had to limit them to two rooms of the house so the carpets don't get ruined but really don't want this to be for very long.

We have spoken to a vet but he's at a total loss as to why this could be happening. Is it possible that after 4 years of having the op, some hormones have been released again if the op wasn't performed correctly? Or is there something else that could be making him behave like this? We're worried that his brother is going to get aggressive if this carries on and this will permanently damage their relationship. Oh, forgot to say, we have separated them for an hour at a time just so the non horny one gets a break! Sometimes he goes and sits upstairs on his own but other times he seems to want to get back to where his brother is. Any advice would be much appreciated, we don't know what to do next!

Dear Emma,

One possibility for recurrence of hormonal behavior in a neutered male is an adrenal tumor.  These are usually not metastatic, but they can cause all kinds of problems, such as the ones you are describing.  This can be diagnosed via radiography or ultrasound.  A blood test for hormone levels might also be instructive.

Fortunately, treatment with Lupron is often very effective at alleviating the signs of this disorder, so you might wish to ask your vet about that.

I hope this helps.



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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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