I tried that with my Echo, and it responded "Hmm...I don't know what you mean".... nothing about buying dog food. But I think you just didn't ask the response

I tried that with my Echo, and it responded "Hmm...I don't know what you mean".... nothing about buying dog food. But I think you just didn't ask the response that the developers anticipated -- I asked "Alexa, do you like dogs?" and it responded "I don't have a dog, but if I did, I would name it Astro".