Cats and Dogs Could Be a Bigger Environmental Threat Than We Thought

A new report suggests that cats and dogs in the US eat as much food as everyone in France does each year, producing 64 million tons of carbon dioxide.

Americans own an estimated 78 million dogs and 86 million cats, and those pets are well-fed. The pet food industry in the United States is an $18 billion business with an increasing amount of sales coming from “premium” and “gourmet” products that claim to contain more meat — even human-grade cuts of beef, chicken, and pork.

Unfortunately, meat has a sustainability problem. Raising animals for food consumes tremendous amounts of water, uses up arable land, and produces climate-warming greenhouse gases. An estimated 18 percent of global greenhouse gas emissions are tied to livestock production, according to the Food and Agriculture Organization of the United Nations.

Sustainable food production is usually thought of in human terms, but a new study claims that America’s pets are an overlooked part of the problem. According to Gregory Okin, a geologist with UCLA’s Institute of the Environment and Sustainability, the meat consumed by America’s dogs and cats is as much as everyone in France does each year, producing 64 million tons of carbon dioxide.

"I like dogs and cats, and I'm definitely not recommending that people get rid of their pets or put them on a vegetarian diet, which would be unhealthy," Okin said in a statement. "But I do think we should consider all the impacts that pets have so we can have an honest conversation about them. Pets have many benefits, but also a huge environmental impact."

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Okin is particularly concerned about the anthropomorphism of animals and how that’s driving consumers to seek out pet food with more and better cuts of meat. Citing pet food industry surveys, he found that 38 percent of dog owners and 30 percent of cat owners say they buy “premium” or “gourmet” brands that claim to contain more meat.

To calculate the environmental impact of pet food, Okin first had to estimate how much pet food America’s dogs and cats eat on average each year. He then used the ingredient lists from dry pet food packages to figure out how much of that pet food was derived from animals: beef, chicken, pork, and fish. In the end, he estimated that 33 percent of a pet’s diet comes from animal products, compared to only 19 percent in humans. That meant that dogs and cats consumed 25 percent of all animal-derived energy in America, the equivalent of 62 million humans.

On the surface, those are troubling numbers in terms of sustainability, but the situation may not be as dire as Okin suggests. Kelly Swanson is a professor of animal and nutritional sciences at the University of Illinois at Urbana-Champaign, and wrote a 2013 paper on the environmental impact of pet food. Reached for comment by email, Swanson said that the new study overlooks one critical fact: Most of the meat in pet food is a byproduct of the human meat industry.

When animals are processed for human food, there’s lots of stuff left over: offal (organs and other unwanted parts), skin, fat, bones, feathers, blood, and more. The rendering industry takes all of this waste — which would otherwise we dumped in landfills — and produces 25 million tons of animal byproducts each year, things like bone meal, feather meal, blood meal, and protein-rich fats and greases. The majority of these byproducts are used in livestock feed and pet food.

Swanson’s issue with the new study is that it calculates the environmental impact of meat in pet food as if the pet-grade meat required the same number of cows, chickens, and pigs as human food. More accurately, the meat in pet food is a byproduct of the very same animals being raised for people.

“[Secondary animal-based ingredients] cannot be considered to have the same environmental cost (e.g., carbon footprint; water footprint) as those of human grade quality,” Swanson wrote. “In fact, the use of these products has a huge positive environmental impact on the human food industry.”

That’s not to say that Swanson thinks that pets are 100-percent sustainable. He’s more concerned with what he calls “nutritional sustainability” and how we may be wasting valuable nutrients by overfeeding our dogs and cats. More than a third of all dogs and cats in the US are overweight or obese. Part of the problem isn’t just giving our pets too much food, but giving them food with way too much protein.

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According to the National Research Council, part of the National Academies of Science, Engineering, and Medicine, 10 percent of a dog’s diet should come from protein, and 20 percent for cats (cats are pure carnivores, while dogs are more omnivorous). In his 2013 paper, Swanson cites other studies indicating that commercial dry pet food contained 31.4 percent protein on average and canned wet food contained 40.8 percent protein, far higher than the recommended intake.

Swanson believes the pet food industry takes sustainability seriously, but would like to see adjustments to the amount of protein in its products. He would also like to see more studies of using plant-based proteins like soy to supplement some of the animal-based byproducts, without sacrificing the health of America’s beloved dogs and cats, of course.

In the new study, Okin predicted that some critics would object to his calculations on the basis of pet food being made from byproducts of the human meat industry, but he argued that the distinction between pet food and human food may be artificial.

“The argument that dogs' and cats' environmental and energetic impacts are obviated by the fact that they eat byproducts from the human food system, and that otherwise the material would go to waste, relies on the assumption that these same byproducts could not be made to be suitable for human consumption after suitable processing,” Okin wrote in the paper.

In his statement, Okin cited the public outcry over “pink slime,” the meat byproduct allegedly used to make school cafeteria hamburgers.

"It's perfectly edible and completely safe, but it's unappetizing, so people don't want it in their food," Okin said. "But frankly, it's a good, inexpensive protein source."