Hello, there. Sorry to hear that Harvey wasn’t doing so well.
I would not recommend giving your bunny any medication that isn’t prescribed by your vet. If you do not trust your vet’s opinion, then get a second opinion by a new vet. Do not risk your bun’s health by potentially using the wrong medication to treat a prospective illness.
Now, I do recommend getting a culture test done to confirm the Pasteurella diagnosis. Otherwise, it’s just all spectulation. Once you know what it is (or what it isn’t), your vet can decide on the proper course of treatment.
I recently had a Pastuerella scare, too. My bun developed a runny nose and sneezing about a week after I adopted him. I took him to a vet and had a culture test performed. The culture test was simple — it was basically just a nose swabbing. It took all but 10 seconds. A vet technician held my bun while the vet swabbed his nostrils. That’s it. The swabs were contained and sent back to a lab for testing. My bun wasn’t put under sedation. Since it took a week for lab results, my vet prescribed Baytril as a broad spectrum antibiotic.
It is my opinion that any experienced vet should be able to perform a culture test without putting your bun under sedation. Now, your vet may have been reluctant to perform a culture test if your bun doesn’t like being handled, can’t be held still, or was exhibiting signs of stress during the vet visit. Regardless, I highly recommend getting a culture test done one way or another.
In my case, my vet prescribed Baytril because it is a broad spectrum antibiotic. Turns out, it wasn’t Pasteurella but Bordetella, which is treatable. My bun is recovering well, and he no longer has any previous symptoms. So, the Baytril was beneficial for my bun.
Good luck! Hope Harvey feels better soon.