[sweetlee]

I don't know about colitis, but my vet said that dogs just like people can have IBS. I believe mine is one of them. He wanted me to put him on one of the Hills prescription diets and if I hadn't gotten the mushy poop and bouts of the runs under control I would have done it.
I have gone the rice boiled in chicken broth route, and then someone said bran flakes on his food would firm up his poop and it did, but he had icky eye boogers, so I figured he was allergic to that.
The pumpkin helps lots of people, and others just say it makes orange squirts, I mixed it in with rice and Dodge did OK on it, some improvement but still mush.
One thing I have found to help is oatmeal. It seems to work better than rice, have you seen the glue like texture of it after it has cooked and cooled? My dog likes it, where as the rice I had to boil in chicken broth to make him like it unless he was absolutely starving.
There are also natural probiotics which you can try, I use a product called dogzymes, it contains natural bacteria which are essential for a healthy digestive tract. GOOD bacteria, that is why I take it myself whenever I am on a course of antibiotics, because they will kill of the necessary bacteria in the body along with the bad ones, ending up with diahrrea, or yeast infections.
While the bloody mucousy stuff is not just IBS maybe while that is clearing, and you are using the meds, you can try some of the above tips, including the prescription diet. One thing at a time though, so you will know what does or does not help.
I know it's tough, and my dog is only about 1 1/2 years old, so looking forward to a lifetime of that was freaking me out. He is now on Canidae lamb and rice formula, and I do make one serving of oatmeal a day, and split it between his two meals, mixed in with his food and add 1/2 tsp of the dogzymes in. I don't allow greasy treats, the most fat he gets from treats is in the form of the mozzerella string cheese, less fat than most cheeses.
I also read in the nutrition/grooming forum that there is something called olewin carrots, that is supposed to firm up the stools. I believe that that and the oatmeal are high fiber and will draw in some of the excess liquid in the digestive tract. I think I am going to give those a try.
I really hope that your sweetie gets to feeling better soon, and that you can find a balance of things that will get this under control.
Let us know.

Sharon