Its very derivative of this I think..
Also this is just mediocre derivative music to relax humans with shit taste. What is there to specifically relax dogs? Maybe the human present relaxes and the dog senses the mood change ans also relaxes.
There could be all kind of cool sciency stuff using frequecies we cant hear that you would need special speakers/amp/source to play
My first guess is it's bullshit. My second guess is that it's got something to do with high-frequency sounds. If you notice, near the beginning of the song, there's an odd high pitch whine that gradually gets higher and higher until it pops out of human register. I checked out a couple more of their SONGS TO RELAX DOGS BY, and they all have this same feature. So perhaps there's an ultra-high frequency drone here that dogs find orgasmic?
That high frequency whistler was like a pin being pushed into my ear drums. Wear headphones, and you'll notice the sound moves around. I presume this is to get the dogs attention, and the foolish owner thinks "Oh look the dog is looking at the speakers, it must really like the music" just like the old RCA record logo.