Domesticated dogs have adapted abilities such as directional and highly acute hearing, the digestion of starchy foods, a strong sense of smell, far-sighted vision and the ability to see more effectively in the dark. These adaptations helped dogs survive among humans and also make dogs more useful.
According to the Merck Manual, dogs have the ability to distinguish the directional origin of a noise. This is an adaptation that is useful for hunting, because dogs can hear the sound of prey attempting to flee or hide, even if they cannot see their targets. The physical part of this adaptation involves a deep ear canal, which gives dogs superior hearing when compared with humans.
Northern Virginia Community College further points out that dogs' eyesight adaptations have contributed to their success. Though dogs cannot see much in the way of color and aren't very good at distinguishing detail, they do have a superlative ability to detect movement with their eyes, a trait that is useful for hunting and guarding.
An article from Davidson College discusses the idea that the dog's ability to digest starchier foods than its wolf ancestors also contributed to its ability to live with humans. Dogs have developed digestive adaptations that allow them to process and gain nutrients from grains and potatoes.