Pasteurella vs. E. cuniculi?

Question
I just had to put my 6 yr old bunny to sleep today. I am very upset. I just don't know what went wrong. I'm wondering if you can help piece together what was wrong with her.
Sunday- opened cage door and bunny was lying on side in cage, unable to sit up, had very rapid vertical nystagmus. Got her set-up in a box, still eating greens. Started her (on my own) on 70mg of fenbendazole (10 lb rabbit) and .05 cc of Banamine.
Monday- called vet, he was not in. Bunny improving a bit though, lifting head, attempting to sit, nystagmus decreased a lot, weakness seems to be from hind end. Continued with Fenbendazole and banamine 1x per day and scheduled vet visit for Tues.
Tues- bunny much better, vet prescribes 4 ml Baytril 1x per day, he suspects pasteurella, told to discontinue banamine and continue with fendbendazole. Bunny very alert today, able to sit with moderate head tilt, eat grass and greens on her own during day, drinking water on own from bowl,nystagmus completely gone, gave antibiotics at night.
Wednesday- bunny stayed the same, noticed her sneeze 2x
Thursday- head tilt a bit worse, bunny beginning to roll when head tilts to far, slight nystagmus returning, noted increased resp rate, feels very hot. Called vet and told to continue with same treatment and check back in 5 days, told I could try banamine again.
Friday- bunny same as Thursday, as day progresses note grunting noises from her, rolling more frequent and unable to right herself, nystagums is occurring when head tilts to far and now seems to be rotatory, still eating and drinking with assistance. At night, she went into severe resp distress, she was open-mouth breathing. Rushed her to emergency vet- told nothing else they could do for her within my budget and had to put bunny to sleep.
I have her sister at home still. I am very worried this could happen to her too and if it does I'm not sure what to do. Is there anything I can do to prevent this from happening to her sister?  What could this have been? Any hypotheses on why she improved and then went downhill so quickly? I just need some help to bring closure to this.
Thank you so much.

Answer
Dear Becky,

I'm so sorry about this terrible loss.  It really sounds as if you were doing all the right things, but your bunny's body just could not respond to heal itself.

Head tilt such as what you describe can have various causes, as you know.  Dr. Susan Brown gives a good overview here:

www.rabbit.org/health/tilt.html

Yours could have been due to either E. cuniculi or bacterial infection--not possible to say without more information from a post mortem exam with histopathology and cultures done on any abscessed material.  But the fact that she may have spiked a fever suggests that this could have been bacterial in origin.  An ear infection *can* become systemic in some cases, often simply because the rabbit's immune system is not up to the task.

If this was a bacterial infection, it was not necessarily Pasteurella.  Though this bacterium is common in rabbits, it's not the only pathogen that can cause these signs.  And since she was on Baytril and it proved ineffective, then this was either NOT Pasteurella, or it was a strain of Pasteurella that was at least partly resistant to enrofloxacin.  We've found that injectible Penicillin-G Procaine can be very effective against Pasteurella once it's started to cause a fever--but that doesn't always work, either.  Sometimes combining Penicillin injections with Baytril (we actually no longer use Baytril, and have switched to its bigger, badder cousins zeniquin (marbofloxacin) or Dicural (difloxacin)) can work very well.

I mention all this because there is no real way to prevent this from happening to your other bunny, but if it *does* happen (which is not all that likely, since bacterial pathogens don't readily pass among adult rabbits), you'll at least be armed with a bit more artillery.  Please also read:

www.bio.miami.edu/hare/sickbun.html

so you'll know how to take body temperature, which can tell you a LOT about what the next step for emergency care will be.  

I'm sorry about your loss.  Her sister will be grieving along with you, so be sure to give her lots of love.  Stress of grief can predispose anyone to illness, including a bunny.

You really were doing all the right things with your bunny, and it is very sad that she didn't respond to the medications.  Sometimes there is just no clear reason, and we have to accept that we are only mortals trying to thwart the Black Rabbit as long as we can.  But sometimes he just will not be denied.  I hope you can take some small comfort in knowing you really tried everything, and that she had a lifetime of love, even if it was too short.

Once you and your bunny have healed from this sadness, you might consider letting her choose a companion from among the needy fosters at your local rabbit rescuer's foster home:

www.rabbit.org/chapters

Once she has a bonded pal again, she will be happier, and that will mean she also will very likely be healthier, and you'll have less worry.

I hope this helps.  

Dana