The results are in from UW Madison from the necropsy. It’s coccidiosis
The vet has me giving corid for treatment and a preventive. I might try a feed additive as a preventive also.
A friend of ours bought some rabbits at an auction a few years back and that is when we started having problems with the weaners. A learned lesson to keep a closed herd and only being new breeding in from a reputable rabbit breeder. I’m discouraged…
Any input on a preventive? I don’t think an antibiotic is the long term solution. Or is there no solution? I have my rabbits in an old dairy barn and it’s not possible to sanitize everything.
Your original posts sounded like coccidiosis to me. "Weaning enteritis" is often due to coccidiosis, which can strike as early as three weeks and as late as 10 weeks. I'd agree with your reluctance to use antibiotics for the long term; I'd definitely be hesitant to use Corid as a preventative. Eventually you may end up seeing amprolium-resistant coccidia. In fact I believe one of my daughter's friends is seeing just that in her herd of Rex.
In my experience, coccidiosis is often, or even usually, due to hygiene issues, most often related to wetness. Definitely clean out cages and hutches that have held sick rabbits to reduce the number of pathogens, but you should not have to sanitize everything in your barn all the time; healthy rabbits should be able to withstand some minimal exposure to common pathogens. Coccidia, like many bacteria, produce symptoms after a certain level of exposure combined with an individual's lack of resistance (due to stress and/or genetic predisposition). Since you seem to be careful about hygiene, and describe all the bunnies having similar symptoms with mostly the ones that are moved being the ones that actually die, it sounds like you've got an inherent weakness that is exacerbated by the increased stress of moving.
My suspicion is that rather than the auction rabbits bringing pathogens into your barn, they brought a genetic predisposition to suffer from the bacteria into your herd. Instead of giving up or closing your barn in an effort to completely eliminate pathogens (you won't be able to, anyway), try to breed more resistant rabbits. If you have any babies that do
not become symptomatic, those are the ones to keep. If you have none at all that don't show symptoms, second best is to keep the ones that became symptomatic but recovered, and work from there, with your goal being complete elimination of symptoms. If you think you have traced the root of the problem to the auction rabbits, you might think about replacing some of your breeding stock, maybe a few at a time so you don't throw the baby out with the bathwater. Getting rid of descendants of the auction rabbits might be a place to start.
I briefly had a problem with weaning enteritis/coccidiosis a few years ago. It persisted until I went back to a zero-tolerance policy: any bunny that has any gut problems whatsoever does not make it into the breeding line-up, no matter how pretty. It does not take many generations to produce nearly 100% resistance to weaning enteritis if robust health in breeders is non-negotiable, assuming good hygiene practices of course.
My barn could not really be farther from a closed system - I swap breedings with friends, and we take our rabbits to shows, fairs, petting zoos, etc., but I rarely have health issues in my rabbits. I believe it is because I leave very little room for problem animals (health or temperament) in my breeding lineup.