Yesterday I was at my local supermarket buying a large bag of Purina dog food for my loyal pet and was in the checkout queue when a woman behind me asked if I had a dog. What did she think I had, an

The woman behind you probably expected that you had a dog because you were purchasing a large bag of dog food, which is a common assumption. Her question, "Do you have a dog?" was likely intended to strike up a conversation or to confirm her assumption, given the context of your purchase.

In response, you could have simply said, "Yes, I do have a dog," or you might have clarified that you were buying the dog food for a friend, neighbor, or a local animal shelter. It's a friendly and common ice-breaker to start conversations with strangers in public places like a supermarket. The sentence may have been cut off, so it's uncertain what she might have thought you had if you didn't have a dog, but her question was likely just a friendly inquiry.