Obviously, dogs do not speak any certain language, but they can understand them. If you raised a dog in Germany since the day it was born, it would only know the German language to which it was used to responding. The same if you raised a dog in America or any where else.
Take my dog, for example. We bought this little chihuahua from a Mexican man from Mexico. You could talk to that dog all day and it would never do anything you said. It would just look at you like you were stupid. After I began dating a Mexican, I picked up on some Spanish, and started talking to the dog in Spanish. Only then would the dog sit, lay down, go away, go outside. So to a certain extent, yes, dogs can UNDERSTAND English or any other language, IF they are raised with that language.