Interestingly, there is a huge incidence of IC with cats. Very strangely, my cat, who, I shamefully did not spay in time got pregnant and had a litter of not one, but, five kittens earleir this year. I found homes for all of them. The one I kept apparently has, yes, IC. So, I have treated him. He instantly responded positively, but then after about 10 days, began to have symptoms again. Then I realized, I had not changed his water. I did so and since then, which has been another ten days, there have been no symptoms. 

This poor cat was trying to tell me something by peeing repeatedly on my bed. Finally after I didn’t fix his problem, he started peeing ON ME! That’s when I said to myself. “OH, he is trying to tell me something!”
I thought he was just being naughty.

So, if your cat is having problems with urinating inapporpriately, it may be IC. While that is also my point, the very most interesting thing here was the water!

Dr.M