You get special rabbit panacur which is a paste in a tube that you give for 9 days as a preventative. The makers say to use it 4 times a year, but that seems a bit excessive. You can also get it in liquid form, which works out cheaper if you have a lot of rabbits/use for a longer period, but I don't know much about that kind.
As I said, it is used mainly to protect against EC, which a large percentage of rabbits carry. They can pick it up from other rabbits through spores in the urine, from their mothers when they are still babies etc. Usually it lies dormant, but in others it can cause problems. My two are house bunnies, but I am going to treat both of them. Bailey is having his 9 day course now, Luuna will have hers later as she is just coming off antibiotics. Its better to treat at the same time, but my two don't live together anymore.
Longer courses are used to treat for suspected EC, which can cause symptoms like head-tilt, excessive drinking and urinating and can ultimately be fatal.
If you use the search facility on here you will find out more about it, I'm not that knowledgable about it
Sorry for the long post! :wave: