If you expect an in-depth analysis then brace for a disappointment. This is just an honest question to which I have no satisfactory answer. I however consider the fact quite annoying in the context of dating. What a photo of a woman with her dog says to me is “I have an emotional bond to this creature that requires my near constant attention.”
Though a simple survey among men (sample size = 3 ) supports my position, I'm going to speak for myself. What I'd like to have is a relationship with a human female and relationships with humans are complicated on their own, so let's keep each other company.