finn has very long hair around his rear end and if he has runny poo it all gets caught in his rear end. I've generally got a bucket of water, a jug and some gloves and rinse it until it's all out... He doesn't like it one little bit, poor thing, it's very undignified, after all!

changed his food tho, and we havent' had a runny poo problem since.

Sgurr is right, it's very important not to pull if it's only half in/half out...

best of luck!