Living in TX, we grew up around yaupon Holly, and were always told it was poisonous to people and dogs. Also, it was known as a deer resistant plant for landscaping.
NOTHING is deer proof, only deer resistant.... I think the dastardly beasts will eat wood. I’ve had to weld cages for any plants I don’t want eaten by deer.
I know it was the yaupon that caused the kid to throw up because there were little yaupon leave bits all in the lunch chunks and skittles and other junk he ate.... like cutting open a shark. You got to see what he ate the last day.