Yeah, Martha is an Old English Sheepdog, and I am pretty sure that the whistle at the end of "A Day in the Life" is a fact. However, I will also say that I used to play it for my sister's miniature schnauzer, and he never reacted at all (this was like 25 years ago). I have never tried it with Ginger, maybe I will have to dust off those old LPs.
Here is picture of Paul and Jane with Martha.