The term color blind is, therefore, somehow misleading. Some animals developed the ability to see some colors and others to see other colors all depending on what mutations appeared and the subsequent costs and benefits each strategy implied for their struggle for survival.

What does this mean for our communication and training of our dogs? Since dogs find it difficult to distinguish between certain reds and greens (like some humans do), we should choose toys and training aids in other colors. For example, light blue or yellow are much easier colors for a dog to detect. On the other side, when training them in any scent detection discipline, we should use colors for the targets that are difficult for them to see so to compel them to use their noses and not their eyes.

References

Kasparson, A. et al. 2013. Colour cues proved to be more informative for dogs than brightness. Proceedings of the Royal Society.