I am attending a pet grooming school and this sweet little old (12 yr old) poodle had this all over her teeth. I first noticed her horrid breath and decided to take a look. ICK..... it still gives me shivers. Its the grossest shades of green, brown, and yellow, hard as a rock, and sometimes has really rough and raised surfaces. I have seen it a few times on dogs but would like to know what the heck this stuff is. My instructors tell me it is plaque and tartar build up that could have been prevented if the dogs had been fed hard food more often, or had had things to chew on. What is the treatment for this??? Can chew toys and kibbles be the only thing causing this? Can the introduction of them help improve the condition??? YUCK!