Deer: When Deer are hungry they will eat almost anything, including the thorniest Epiphyllum you have in your garden.
Solution: There are many products on the market for repelling deer. From ultrasonic fencing to sprays and pellets; we have had customers report good results from using sprays containing coyote urine in them.
Deer do not like plants that irritate their stomachs we have heard sprinkling hot chili pepper on your plants or spraying them with a solution made of blended habanera peppers also works as a deterrent. If trying one of these keep in mind they will eat some of the plant before finding it distasteful. Also if they are hungry enough they will eat the plants regardless.