Call it anthropomorphism, or more accurately, call it a lucrative market. Dog owners are a marketer's best friend - even when the task at hand isn't pushing pet products. Despite their high maintenance, dogs remain the most popular pet in the United States, with 45.6 million households owning 77.5 million canines, according to the American Pet Products Association's 2009/2010 National Pet Owners Survey. They're a spendy bunch, forking over an estimated $45.4 billion in 2009. The lion's share of that goes to food, but the APPA expected spending on general supplies and over-the-counter medications to total $10.2 billion.