Unless there are other symptoms your rabbit is having, or findings by the vet that haven't been mentioned, I think you need to find a different vet. Those symptoms are not something that would indicate steroids and antibiotics are the correct medications to be using, or that a bacterial infection in the colon is what is really going on and the cause of your rabbits problems. A bacterial infection of the colon would almost always cause diarrhea, not a lack of pooping
Along with the fact that steroid use in rabbits is considered a last resort medication because of the severe negative effects that it could cause. Any halfway knowledgeable rabbit vet would know this and NEVER administer steroids to a rabbit that was suspected of having any sort of bacterial infection, due to the fact that steroids depress a rabbits immune system, which is the last thing you want to be happening when there is an infection occurring.
Medirabbit: Corticosteroids, best avoided in rabbits
So if there weren't other symptoms or findings that would indicate steroids were absolutely necessary and the proper medication in this case, in my opinion your rabbit received an incorrect diagnosis and incorrect medicatioins. In the very least your rabbit should have been treated for GI stasis with gut motility meds, meloxicam(NSAID), and sub q fluids(if dehydrated). And a proper evaluation to determine if it was due to a simple stomach upset or slow gut motility due to diet, or if there was some other underlying cause for the stasis occurring.
https://rabbit.org/gastrointestinal-stasis-the-silent-killer-2/
https://rabbit.org/sluggish-motility-in-the-gastrointestinal-tract-2/
As for the cause of the lack of appetite and not pooping returning after 5 days, I'm guessing that it's not due to the antibiotics, but because the steroid injection is wearing off and your rabbit is starting to experience pain again. This would mean that something is causing your rabbit to be in pain, and that is causing the lack of appetite, and cooresponding lack of pooping. Provided there isn't more info about your rabbits condition that hasn't been mentioned in your post, that would be my guess as to what possibly could be going on. If this is the case, it would mean finding the underlying cause of pain that is leading to the GI stasis occurring. So your rabbit may need to have a blood test done, and possibly further xrays may be needed. Along with a thorough dental exam first being done, to make sure that's not the underlying cause of pain.
I personally would
not go back to that vet, and would try to find a more knowledgeable rabbit vet, even if I had to drive a bit to get there.
https://rabbit.org/vet-listings/
