I grew up in the Houston area, speaking a sort of Texan version of English. I spent years,especially when I was a radio announcer, ridding myself of what accent I had, learning to speak a generic Middle American English. Possibly as a result of this, I have a pretty good ear for regional dialects, and can usually guess where someone is from after a few minutes of conversation.
In addition to English, I took two years of high-school Spanish, two years of college French and one semester of college German. While I never got particularly fluent in any of them, I did reach the point where I could make sense of either the French or Spanish versions of Reader's Digest.
I say all this to establish the fact that I have adequate language skills, but I realized long ago that my abilities don't hold a candle to our Dachshund Dusty.
By the time she was two months old, she already recognized words like "outside" and "treat," and her vocabulary has continued to grow over the years. I honestly don't think that there is anything I can say that she doesn't understand.
I can claim to understand some of the things she says, but honestly, I don't. It's always a guess arrived at by process of elimination.
For example, one of her quirks is that if she can see even a portion of the bottom of her food bowl she will come and demand that I fill it up. Like the American in China who can't be understood will resort to speaking the same English words slower and louder, she will continue to repeat the same sequence of barks until she gets what she wants.
After twelve years, you might think I would understand her, but she could just as easily be telling me that my fly is open or the house is on fire.