I have a 4 month old Shichi( shih tzu chihuahua mix). He pooped at the bottom of the stairs and it looks like diarrhea. Also when I went in the bathroom their was poopy liquid in a puddle on the floor. As gross as it may sound. I really want to know what's wrong with him. Could he need to have his heartworm medicine? he has full access to food and water all day so he can't be dehydrated. Please help!