When a horse is twenty yrs . old the groove should reach down into the bottom of the teeth. You should brush your dog's teeth everyday but if you do it daily, once every 2 days is well. Never put this off, already extremely in order to the health of your animal. https://privatebookmark.com/story17796222/the-need-for-dog-oral-%EC%9E%90%EC%9C%A0%EA%B2%8C%EC%8B%9C%ED%8C%90-ml