Innekanin.

I've been raising and showing rabbits for 25 years. There could be a couple reasons:

1.) Flip your rabbit over and see if it has diarrhea. The #1 reason why most rabbits stink is because they have a case of diarrhea. If I ever smell stink coming from one of my rabbits, that is the very first thing I do. If you are feeding any treats, vegetables, greens, grass, fruit, etc besides your rabbit pellets and water. Stop feeding them. They can cause diarrhea. You might also want to consult with your vet just in case the diarrhea is bad.

2.) If you see a brown stain on the rabbit's coat, that could be due to urine. Rabbits normally get urine on them via one of two ways. Either the rabbit is a male and is peeing on the sides of his cage then rubbing against the cage wall. Good evidence of this is to look at the cage wall and see if you see urine stains on the wall. The second way is via a male that is penned next to the rabbit. The male that is next door may be peeing on it.

3.) The third reason is not as common, but can occur. The third reason is vent disease. This is a disease of the vents which are located to the left and right of where you determine the sex of the rabbit. The smell will normally emanate from the vents and normally a milky type fluid will be coming out of the vents.

4.) The rabbit could have maggots eating at its underside. This is somewhat rare but can happen.

5.) The rabbit could have an abscess that has burst. This also would be rare. Depending on the type of infection, some puss in an abscess has a distinct type of smell. One of my rabbits once had an abscess and my vet could tell by the smell what type of infection it was.

As far as cleaning your rabbit, use a cloth soaked in white vinegar and wrung out till it is just damp. The white vinegar will help cut through the stain. Then use a moist towel soaked in water to rinse the vinegar.