Colloidal silver is the best thing for not only shrinking but getting rid of tumors. Are you referring to a fatty tumor? If so, colloidal silver will do the trick. It literally melted my 9 year old Misty's tumor in less than a month and in the process gave her the vim and vigor that she had in her puppy days.
Actually, despite the type of tumor or the type of condition your furbaby may have, I highly recommend colloidal silver. It has healed every condition that any of my pets ever had. In fact, within the last two months it healed my friend's puppy that had Parvo.
Misty now takes colloidal silver every day as a preventative to insure optimum health.