The American dog tick is grey and looks like a bean when it is engorged with blood, according to Pet 360. When not engorged, they are brown with white streaks or spots on their backs. Brown dog ticks and deer ticks are both brown in color when engorged with blood.
According to the Centers for Disease Control, the American dog tick lives all over the United States east of the Rocky Mountains. They can also be found in a small area on the Pacific coast. The dog is the preferred host of the American dog tick, but they also attach to humans. American dog ticks can carry Rocky Mountain spotted fever and tularemia.