These are panties for my intact girl dogs when they come in season.
They are made from PUL. I have made them in the past with cotton prints and flannel lining.
By making a slit from the edge to the tail hole, the binding is much easier to apply. With the way the hole is overlapped, it makes getting the pants over the tail easier. The panties can be rinsed off when needed or an adhesive pantie liner can be inserted. They are closed with Velcro.
Instructions on-line for PUL diaper covers can be used to learn the details for working with PUL.
I found the supplies for diaper cover making at JoAnn's near the buttons.