Blood in rabbit urine from food change

Hello. I have had my rabbit for about three years now, and for his whole life I have had his bedding be hay, i have only had to use straw once or twice because i ran out of fresh hay. He has NEVER once been ill because of this. I understand that it is advisable to use more straw than hay, but this has never affected my rabbit.

I also read here about food that can upset their systems. One that you have not mentioned is (one I don't know the name of, if it even is a disease) is if you were to change their diet from one type to another within day or two, then it puts stress on their systems and they end up urinating blood.

I have experienced this myself. I was very scared because it seemed serious. But I didn't visit the vets. Instead I spoke to the man who gave the rabbit to me; he knows plenty about rabbits and sometimes breeds them. He told me what the problem was and that it can easily be fixed by mixing the foods evenly, while adding more of the new food a little bit every other day. Most people know this as 'weaning.'

As a p.s. I would like to thank the people who made and run this site. It has been so helpful to me for future care of my rabbit, I have learned so much and I am very thankful to know that there is some sort of site I can read and rely on for basic but realistic facts.