One of mine has been troubled with this since being young, I did have another one who had it too.
My little one is on Salazopyrin twice a day & I have to be very careful with her diet. Emotional upset always triggers a bout, especially if I have to leave her for more than an hour for some reason, so she mostly comes everywhere with me.
This is a very interesting article.
Colitis, a Specific Cause of Diarrhoea | Cynologist