“Cats wag their tails as a form of communication, but unlike dogs, it's not always a sign of happiness,” explains Cristy Brusoe, a certified cat trainer and founder of Cat Training by Christy.

An curved arrow pointing right. We know why cats love boxes and why dogs howl. One thing both pets like to do, though, is to chase their own tails. ASPCA science advisor Dr. Stephen Zawistowski ...