For Glenn Rankin, eating dog food is just part of a day’s work.

As managing director of British startup Yora Pet Foods, Rankin’s job is figuring out how to lure dogs — or at least, their grocery-shopping owners — away from traditional pet fare that contains animal meat. His company’s kibble, made from black soldier fly larvae, “tastes a bit like Stilton [cheese] on biscuits.” (Gizmo, Rankin’s five-year-old labrador, who switched from chicken-based pet food to an insect-based diet in 2020, was unable to comment.)

Livestock is responsible for roughly 14.5% of global greenhouse gas emissions, according to the United Nations. A lot of that is for human food, and some of that is for pet food. How much? Looking at just the US (the world’s largest market of pet owners), one 2017 study found that if the nation’s 163 million pet dogs and cats formed their own country, its meat consumption would rank fifth in the world. Another study, from 2020, found that the global production of pet food emits annual greenhouse gases on par with the Philippines.

Read More: A New Study Ranks the Climate Pawprint of Different Types of Pet Food

For a handful of startups including Yora, the solution is simple: Change what the world’s pets are eating. Since 2015, Yora has been developing insect-based alternatives, which it now sells in more than two-dozen countries. Rankin says sales almost doubled in 2022, to £2.2 million ($2.7 million) from a year earlier.

Vegan dogs and death threats

Bugs aren’t the only option on the menu. Shortly after Wild Earth co-founder Ryan Bethencourt introduced his plant-based dog food on US reality show Shark Tank in 2019, “I got death threats,” he says. The overwhelming theme of the feedback, including from the show’s judges, was that dogs need to eat meat. Billionaire entrepreneur Mark Cuban was the only “Shark” to invest in Wild Earth, “betting” $550,000 in exchange for a 10% stake.

That gamble may look like less of one now. Last year, Berkeley, California-based Wild Earth sold $12 million worth of plant-based dog food in the US, up 2,300% from 2019, according to Bethencourt. The company’s 14 products include peanut butter dog treats as well as dog food made from dried yeast and vegetables. Bethencourt says internal surveys show that Wild Earth’s customer base is evolving, too: It’s no longer dominated by vegetarians and vegans.

San Francisco-based V-Dog, New York’s Bramble Pets, and Gather, a brand created by pet food producer Petcurean in Chilliwack, Canada, are all selling similar products. Globally, sales of vegan dog food hit $12 billion in 2021, according to consultancy Future Market Insights, and are projected to see 7% growth over the next decade. Similar growth is expected for insect-based pet food — global sales there hit an estimated $7 billion in 2021 — though both remain minor compared to $105 billion in annual global pet food sales.

Read More: Hold That Bone: More Owners Are Making Their Dogs Go Vegan

The industry’s biggest players are also signaling interest in protein alternatives. Nestle SA’s Purina is experimenting with dog food made from Asian carp, an invasive freshwater fish prevalent in American waterways. Mars Inc., which owns pet food brands such as Pedigree and Royal Canin, in 2021 added an insect-based cat food line called Lovebug. (Nestle has also pledged to pack all of its pet food using reusable or recyclable materials by 2025, and Mars aims to power its entire operation with renewable energy.)

Ironically, traditional pet food itself addresses an environmental problem: food waste. Most regular dog and cat food is made with off-cuts and meat byproducts that humans won’t eat. To that end, one huge question mark around “climate-friendly” pet food is the degree to which it is, in fact, climate-friendly — or at least more so than the status quo.

Despite a handful of claims made by individual companies with a vested interest in pushing pet-food alternatives, experts say third-party studies are needed to understand those alternatives’ true emissions impact. The sector’s cheerleaders need only look at the dubious history of “organic” labeling on human food to see how easily eco-conscious signaling can be abused.

Read More: Why Consumers Don’t Trust ‘Organic’ Labels

“[We] need some standards for what is climate-friendly,” says Mark Finke, a pet care consultant in Phoenix. “Otherwise, it runs the risk of simply being, however well-intentioned, a slogan or a tagline on a package.”

Peter Alexander, a researcher at the University of Edinburgh who has studied the environmental impact of pet food production, says this tension “mimics the same narrative in human food… Using insects is potentially an option, but it depends on what those insects are themselves consuming,” he says. “Similarly with cell-based meat alternatives, as there is a lot of energy use and infrastructure with associated costs and emissions, as well as questions about the production of the medium in which the cells are cultured.”

For now, those questions aren’t stopping one biochemist’s quest to make lab-grown mice meat for cats.

The other lab rats

Shannon Falconer, co-founder of Vienna-based Because Animals, knows all about skeptical consumers. The startup, which employs people in Austria and the US, once created yeast-based cookies for dogs and supplements made from probiotics for cats, but neither product took off with pet owners. So Falconer decided to apply her biochemistry background to a different solution: making meat-based pet food, but growing that meat from animal cells in a bioreactor. First up, mice.

Cell-based protein gets a lot of hype because of its potential to reduce the greenhouse gas emissions needed to make animal meat, but that potential comes with a lot of big ifs — if the costs came down significantly, if cultivated meat’s energy-intensive production could be powered by renewables and, perhaps most important, if regulators approved it for commercial sale. (So far, the only cultivated meat sold to humans is cell-grown chicken made by San Francisco-based Eat Just, which is available in small amounts in Singapore.) Despite those hurdles, more than 100 companies around the world are working on creating lab-grown beef, oysters and even foie gras for human consumption, with limited success.

Read More: Cultivated Meat Passes the Taste Test

When it comes to pet food, though, Falconer says the economics of cultivated meat make more sense; she even says it’s “both faster and cheaper to make,” as animals are less discerning when it comes to perfecting meat’s look, taste and texture. Growing mice cells for a can of Because Animals cat food takes about 25 days, she says, adding that each can could be sold at a price point “very, very close” to premium meat-based cat food (though she declined to provide exact pricing).

Wild Earth, too, is developing a new pet food made from lab-grown chicken.

But the regulatory hurdles remain. No country in the world has approved cultivated meat as an ingredient for commercial pet food production. (Falconer says Because Animals is targeting the European and US markets, and aims to submit its first application for government review this year.) Current trends also make price parity hard to imagine. Pet food made from insect protein costs roughly five times more than traditional pet food, Rankin says. And while Wild Earth’s plant-based dog food is priced similarly to conventional premium products, it’s about 20% more expensive than average brands.

Convincing pet “parents”

Part of what’s drawing attention to pet-food alternatives is the size of the market: The global ranks of pets are growing. In China alone, where pet ownership has only recently become more popular, families added 42 million dogs and cats from 2017 to 2022, according to Euromonitor International. As with human food consumption, a diversity of palates can also impact the potential of protein alternatives: South Korea, where boiled silkworm pupae are a popular street snack, is the biggest overseas market for Yora’s insect-based pet food.

Read More: They’re Healthy. They’re Sustainable. So Why Don’t Humans Eat More Bugs?

But among the many wrinkles the alt-pet-food market still needs to work through, chief among them may be convincing humans. Unlike cats, dogs can theoretically thrive without meat — but in reality it’s easy to get the balance of essential nutrients wrong. “[The] jury is still very much out as to whether we should be feeding our pets a vegan diet,” the British Veterinary Association noted in a recent commentary.

“Most consumers perceive that their dogs should have meat,” Finke agrees. “Lots of consumers look at ingredient statements. If meat isn’t the first ingredient, they will not necessarily believe it’s in the best interest of the health of their pet.”