Two-thirds of pet-owning households do any type of shopping at Walmart or Sam's Club, with Walmart alone claiming 43 million of 67 million pet-owning households in its customer base, according to data published in U.S. Pet Market Focus: Walmart as Competitor, the third report in a four-part series on Walmart Inc. by market research firm Packaged Facts.

By comparison, Walmart's pet-owning customer base is significantly more than other leading mass marketers Target, Costco and Kroger. These three retailers combined have a customer base of about 35 million pet-owning U.S. households, according to the report.

Packaged Facts found that when choosing a preferred pet products provider, consumers are most apt to weigh factors related to pricing, but factors related to convenience and brands/selection are also important. Less relevant are factors related to retailer staff and in-store services. And while the ability to order online is relevant, other factors related to emerging online ordering trends make less of an impact. In short, Walmart satisfies much of what pet owners seek in a retail experience, the report found.

"Overall, Walmart enjoys impressive strength in shopper traffic/shopping trips, offering almost unbeatable one-store shopping convenience, making it possible for pet owners to pick up non-pet products, along with pet products of all stripes, in the same place. And pet product customers are clearly a growth engine for Walmart," said David Sprinkle, Packaged Facts' research director.

The growth is evident among Walmart shoppers as Packaged Facts estimates that more than a third of Walmart pet product purchasers report buying more pet products from Walmart than a few years ago, while less than 10 percent report buying less, and almost half are buying about the same amount. By demographic, adults in the influential and increasingly powerful gen Z and millennial age bracket (18-34 years old) are especially likely to report buying more products from Walmart than they did a few years ago.