Dog Rocks Â® are a 100% natural, paramagnetic igneous rock mined from a quarry in Australia. They contain no chemicals and have been scientifically tested and proven safe for all pets.
In brief: Water. Free fluid is typically water. The lining of your abdominal contents are slippery (your bowel, the lining of your organs) and it's thus wet inside your abdomen. It's normal to have a little free fluid in one's pelvis, as that's where fluid tends to pool.
Substances have a tendency to diffuse from an area of high concentration to an area of low concentration to balance the difference. When free water molecules do this, it is called osmosis. Water molecules will just slip through the lipid bilayer of the cell membrane because they are so small.