No, dogs aren’t colour blind. However they do not see the same colours as we humans do.
Their sight consists mainly of yellows, blues and violets. This means that they see our reds, greens and oranges as yellows or blues.
So why is it like this?
Well humans and dogs retinas contain two types of photoreceptors; rods and cones. The human eye has more types of cones whilst canine’s eyes have a higher amount of rods and no fovea which is responsible for sharp vision.
This means that dogs have better vision in the dark and have amazing tracking movement but they see fewer colours and see objects in less clarity.