Wolves are one man pets. If you add more human contact they want to get the fuck out of the situation.
Dogs are just wolves that are stuck in the childish phase so they don't develop an adult attitude later in life like cats and wolves do. This has the added advantage of them paying attention to you for longer periods of time so they pick up more words. If you time your orders well when training an animal cats can also learn a wide set of phrases. The main part is making sure you have their attention. Most people exploit the dog's childish behaviour by giving them treats if they comprehend the word correctly.

Dogs are useful because they are a bit stupid. If intelligence was everything then niggers wouldn't be so useless.