
Have found that a change of water will effect a pups system and it could be that if he has the trots as well the bowel lining has become inflamed. Not sure what Colitis means, could be that it just means inflamed large intestine and bowel or it could be a particular illness, will have to look it up.
EDIT well despite the fact that I am eating my dinner I have looked it up and yes, it does just mean inflammation of the intestines so it is possible that the pup has it particularly if it also has the trots.