Dogs are not color blind. In the past, dogs were thought to only see black and white. In fact, dogs do not have as many colors as humans can distinguish. Dogs can’t see red and green, only three colors of “yellow, blue, and gray” can be seen.
Dogs can distinguish between different shades of blue, enamel and purple, but there is no special sensibility for high chroma colors such as red and green in the spectrum. Red is dark for dogs and green for dogs, so the green lawn is a white meadow for dogs.