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Rabbits/E.Cuniculi / Meds


Hello Dr. Krempels,

Hoping you can lend your expertise on a few questions.
Can you tell me how much Panacur and Metacam should be administered to a bunny weighing 4lbs 6oz? I've been giving my little one 0.35cc of panacur for almost 3 years off and on, and just got an updated weigh-in. The panacur is 100mg/ml and metacam is 1.5mg/ml.

After talking to different vets, there seems to be a shift in the knowledge about e.cuniculi from when my rabbit was initially diagnosed.

One vet suggested that when I notice signs of a "relapse" (hind-leg weakness, or a decreased appetite and poop) to just give Metacam until she improves with no Panacur (risk of bone marrow depletion(?)), whereas another vet recommends the 30-day course of Panacur and, if necessary, Metacam.

They've said the organism doesn't necessarily exist in her system any longer, and that the symptoms may be from the damage that was done to her system initially. One vet suggests staying away from panacur for this reason (no E.C. to fight off), while another suggests giving it because it can't do much harm.

Wondering what theory you support, and, if E.C. is no longer present, why would the symptoms mentioned above suddenly occur?

It seems that once I give Panacur, she remains symptom-free for 2-4 months. The most I've had to give Metacam in the past 2 years or so has been 3 days. Do you think it's wise to leave out the Panacur in the future?

Thanks so much for your help. I apologize for the lengthy email.


Dear Jennifer,

Welll...the short answer is:  No one really knows for sure.  Your two vets are on the opposite sides of the spectrum when it comes to Panacur.  What we do know is that fenbendazole is the least toxic of the benzamidazoles commonly used to treat E. cuniculi.  (I would never use albendazole, which has been linked to acute deaths in rabbits.)  The bone marrow problem appears to be most severe in birds, though it's possible that some mammals could get that, too.

Metacam will reduce blood flow to the kidneys, and that's not good for the kidneys over the long term.  Animals with compromised kidneys (as could be the case in an E. cuniculi-positive bunny) might be better off with different pain management, such as an opioid (e.g., Tramadol).

Have you considered trying ponazuril?  We have had very good results in using Pancur and ponazuril (Marquis) together for head tilt suspected to be due to E. cuniculi.  It is pretty benign stuff, from the research that has been done so far.  Jury is still out on whether toltrazuril sulfate (Baycox) is as effective as Marquis, but that's another thing to consider.  (Just don't know if it crosses the blood/brain barrier the way Marquis does.)

If the Panacur helps her, then I'd consider that.  Quality of life is the most important consideration, if you ask me.  But do find out about the ponazuril.  It might be the best option of all.

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:
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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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