Way back, I worked in a feed and pet store. A customer brought in their cat that had a patch shaped just like a heart.
Not a dog or cat but when I was younger on a paper route, there was a bunny in someone's yard with a marking shaped like the number 13 (gangster
bunny?)
I don't have the pics here at work, but our bulldog has a heart on his side. And when our boxer was a pup, she had a mickey mouse head on her nose,
before it went all black.