Study reveals hidden costs of pet food

Gregory Okin is quick to point out that he does not hate dogs and cats. Although he shares his home with neither — he is allergic, so his pets are fish — he thinks it is fine if you do. But if you do, he would like you to consider what their meat-heavy kibble and canned food are doing to the planet.

Okin, a geographer at UCLA, recently did that, and the numbers he crunched led to some astonishing conclusions. America’s 180 million or so Rovers and Fluffies gulp down about 25 percent of all the animal-derived calories consumed in the United States each year, according to Okin’s calculations. If these pets established a sovereign nation, it would rank fifth in global meat consumption.

Producing that meat — which requires more land, water and energy and pollutes more than plant-based food — creates a lot of greenhouse gases: as many as 64 million tons annually, or about the equivalent of driving more than 12 million cars around for a year. That doesn’t mean petkeeping must be eschewed for the sake of the planet, but “neither is it an unalloyed good,” Okin wrote in a study published this week in PLOS One.

“If you are worried about the environment, then in the same way you might consider what kind of car you buy ... this is something that might be on your radar,” Okin said. “But it’s not necessarily something you want to feel terrible about. “

This research was a departure for Okin, who typically travels the globe to study deserts, things such as wind erosion, dust production and plant-soil interactions. But he said the backyard chicken trend in Los Angeles got him thinking about “how cool it is” that pet chickens make protein, while dogs and cats eat protein. And he discovered that even as interest grows in the environmental impact of our own meat consumption, there has been almost no effort to quantify the part our most common pets play.

To do that, Okin turned to dog and cat population estimates from the pet industry, average animal weights, and ingredient lists in popular pet foods. The country’s dogs and cats, he determined, consume about 19 percent as many calories as the human population, or about as much as 62 million American people. But because their diets are higher in protein, the pets’ total animal-derived calorie intake amounts to about 33 percent of that of humans.

Okin’s numbers are estimates, but they do “a good job of giving us some numbers that we can talk about,” said Cailin Heinze, a veterinary nutritionist at Tufts University’s Cummings School of Veterinary Medicine who has written about the environmental impact of pet food. “They bring up a really interesting discussion.”

Okin warns that the situation isn’t likely to improve any time soon. Pet ownership is on the rise in developing countries such as China, which means the demand for meaty pet food is, too. And in the United States, the growing idea of pets as furry children has led to an expanding market of expensive, gourmet foods that sound like Blue Apron meals. That means not just kale and sweet potato in the ingredient list, but grain-free and “human-grade” concoctions that emphasize their use of high-quality meat rather than the leftover “byproducts” that have traditionally made up much of our pets’ food.

“The trend is that people will be looking for more good cuts of meat for their animals and more highprotein foods for their animals,” Okin said.