Dogs Are Colorblind First, no one can see what a dog sees, thus it's hard to know where this belief comes from.
Debunked: Dogs Are Colorblind “Dogs just don’t see as vivid colors as we do,” says doglab.com consultant Sara Ochoa, DVM. The main colors dogs see are yellow and blue.
Since the canine retina has two of the three light receptor types needed to discern color.
Ochoa said grass makes them vomit, but other dogs eat it for other reasons. Sick Dogs Eat Grass—Debunked
A Friendly Dog Has a Wagging Tail Wagging tails are often the best indicator of a happy dog.
The Puppy Academy says it can indicate a dog is friendly, enthusiastic, and ready to play, but not always.
Before assuming a dog is friendly, the Puppy Academy recommends checking for additional behavioral cues including relaxed eyes and ears.