They can, but not as normal humans do. They are colour blind to red and green shades.That's slightly puzzling, because they ought, surely, be able to blood from grass ! The answer must be that ; in reality, that lack wouldn't affect them.They can be excellent at seeing movement; a sight hound pays instant attention to potential, and distant, prey when the prey moves; and are good at seeing in low light. And they have a wonderful sense of smell, which must help them to find and distinguish things with great subtlety. These other abilities serve them better than our colour vision would. The dog certainly knows where the prey is ,and has been, by smell alone !