YouTube link.

This video probably requires an introductory spoiler, because the content will upset some viewers.

A fawn is discovered on a suburban street, where it is investigated (uneventfully) by a housecat.  The doe arrives to guide the fawn away, but then sees a neighborhood dog, and her protective instincts kick into high gear: she ruthlessly pummels the dog with her front hooves.  The cat eventually gets in a final slap and then beats a hasty retreat.

The deer's attack on the dog will distress dog owners, but it serves as a reminder that from a deer's point of view a dog is just a well-groomed coyote threatening her offspring.

(The person who posted the video left a followup comment that the dog appeared to recover from the beating.)