Can you teach an old dog new tricks? Do dogs eat grass only when they are sick?
Of course there are safety-related myths, like "my dog will be okay in the car if I crack the windows". We all better know the answer to that one, and have a role in letting our customers know the facts.
There's "all dogs are colorblind." Reportedly, "the canine retina indicates that dogs can see some colors, primarily blues, yellows, greens and shades of gray"1. (http://www.petful.com/misc/20-ridiculous-dog-myths-debunked/)
My favorite is whether "a wagging tail means a happy dog". My family commonly refers to our dog Gregor's 'wag-o-meter'. We're pretty sure that the more wagging, the happier he is.
Here's the Mythbusters video on the subject: https://www.youtube.com/watch?v=IAv7czgIl0Q
And for more reading, here's a link to Cesar's Way blog on the subject: https://www.cesarsway.com/about-dogs/dog-myths/taking-a-bite-out-of-a-dozen-common-dog-myths
What dog-related myths do you ponder?