I know it can be stressful and im right there with you. I’m dealing with similar issues with two of mine.

I’m glad tallulah is better! Two of mine have pasturella and it will flare up with wet nose and sneezing. The best thing you should do is get Grayson a X-ray to look at his chest to see if there is fluids in his lungs and then go from there. My buns usually go on metranitrozol( butchered that) when they have flare ups.

Bunnies should never be introduced unless they are going to be bonded. The baby could have been a carrier and gave it to him, or he could have had it all along and the stress of a previous illness could have brought it to flare up. The baby should be seen by a vet and can get tested for diseases it has so you can know if you can bond her or not. He should have the snot around his nose sent in for a culture so you can determine what it is and how to treat it. It all costs a lot but it’s better to do it right the first time than to keep trying other ways(trust me?)

Don’t question your care as a parent! Bunnies are difficult to treat and find the cause of illnesses. I’m going through a tough time and I just want to throw in the towel but keep going and keep doing research online so you can be educated and be able to talk to your vet about what you found, and itl make you smarter and heck, it’s fascinating reading about bunny illnesses.
You’re a great bun parent so keep it up

Your vet is right about most buns being carriers of pasteurella. The immune system as a rule keeps it in check, but some buns get sick. It’s not known why. The immune system being challenged by sth else is a theory that seems highly plausible.

Since your new bun is not showing any signs of illness, it wouldn’t have helped to put her in quarantine. She’d still have been a healthy carrier after two weeks in quarantine. It is good to quarantine a new rabbit, but the rationale is that a hidden disease will break out during the quarantine period so you can treat it or take other measures (if it’s sth deadly, think rabies in dogs).

Adding a new rabbit to a household always causes some stress on all rabbits involved. Rabbits are sensitive to new rabbits in their territory. A baby would be accepted though, a baby doesn’t pose a threat. Male rabbits are very protective of baby buns, so it’s not just a female rabbit thing. As Bunny House says, don’t question your care as an owner, the important thing is that you have a good vet and your buns are beeing given appropriate treatment.

Your vet seems rabbit savvy, many vets prescribe a too short course of antibiotics for pasteurella. Pasteurella is often stubborn (as Bunny House also points out). Recovery can be slow and gradual, so you’ll need patience.

Bunnies are great at cleaning themselves so most of the time, we never know if they have snot unless we catch them in the act. The vet can always swab in and around his nose to get a sample and send it off just to see if he has it.

Usually pasturella won’t show up unless it’s flaring up. So she could have it but it not be active in her if she has a good immune system but keep us updated and let us know what you find.

I honestly couldn’t tell you, it just happens usually without any cause so a couple of times a year. I have two others and I just keep them separated.
Unfortunately there is a lot of contradicting information on a lot of stuff for bunnies as they still aren’t quite a lot of studies done on them like dogs and cats. As bam said before most buns have it but some buns have weak immmune systems so only some will show symptoms. It’s just like if I was sick and I coughed on you, you may not show symptoms of the illness but you can pass it to someone and they can show symptoms of it. The little one probably has it if it was from her mom or from Grayson. I don’t know if that helped any.

I’m glad she’s on meds! ( make sure to use probiotics when she’s on it like florentero or bennebac even though there isn’t too much research on wether it helps or not, it might help her since she is a baby) I hope everyone gets better