Hi Huxie,
This is one of the main reasons we stuck with the cx5, DOGS! Ha ha, we carry water, treats and bags, under the floor. Also glass cleaner and a roll of kitchen roll. They do like to wipe their noses on the rear window. One previous cars I had a dog guard fitted, but what I do now is just flip over the retractable shelf to make it harder. Now autumn is here we also carry a towel for paw cleaning.
One thing I have done to both cars is had rear bumper sill strip fitted to protect against paint damage from dog paws with jumping in and out of the boot.