I can see the material you are referring to. It is a little blurry, so I can't tell if the material is more like a mucus, foam, or grainy. This is definitely abnormal and can be caused by a urinary tract infection, mucus in the urethra, or be vaginal discharge. I recommend having Minnie seen by a vet as soon as possible - they can perform bloodwork, x-rays, and a urinalysis to rule out the conditions above. Thank you for using Petco Pet Education Center, formerly Petcoach!