If a cat could choose any kind of animal to eat, what would it pick? That's the kind of question you ask yourself when you're attempting to reinvent the pet food industry from scratch using the latest in biotechnology, as Wild Earth CEO Ryan Bethencourt is doing.

As the longtime program director of IndieBio, the premier biotech accelerator in Greater Silicon Valley, Bethencourt helped companies like Memphis Meats and Finless Foods figure out how to use so-called cellular agriculture to grow edible beef, chicken, and fish from stem cells in the lab. Cultured meat, or clean meat as it's known, promises a way to meet the world's growing demand for animal protein without the necessity of slaughter or the environmental degradation of livestock farming.

Seeing a new industry blossom got Bethencourt thinking about the meat consumption in his own home. An ethical vegan, he avoids meat, eggs, and dairy. But he fosters dogs who need a temporary home, and who eat meat-based dog food twice a day. "I always felt a little guilty about the fact that I don't eat any animals processed in slaughterhouses, but I feed them to my animals," he says.

His animals aren't alone. America's 80 million dogs and 100 million cats consume about 25 percent of all meat sold in the country. And the meat they eat is considerably less regulated than what makes it onto their owners' plates. Often it's from animals that comprise what the meatpacking industry calls the four D's: dead, dying, disabled, or diseased. 

In early March, the J.M. Smucker Co. recalled more than 107 million cans of dog food--sold under popular brands like Gravy Train and Kibbles 'n' Bits--after determining it had used ingredients containing toxic euthanasia drugs. That's even worse than it sounds: Commonly eaten farm animals are rarely euthanized, so the presence of those drugs raised the possibility that meat from horses or even dogs and cats from animal shelters had made it into the supply, as has been known to happen

It was stories like this that convinced Bethencourt and Ron Shigeta, IndieBio's chief science officer, there was a large opportunity here--large enough to be worth leaving the accelerator they co-founded and striking out on their own with a startup. Vegan pet owners are a niche. But people who don't want to feed their pets poison--that's a real market.

Making dog food was the obvious place to start because dogs, as omnivores, are relatively easy to feed. Bethencourt was a fan of Quorn, a 40-year-old vegetarian brand founded in the U.K., which uses mycoprotein, or protein from fungus, as a meat substitute in products like nuggets and patties. In comparison to animals, single-celled fungi are incredibly efficient at converting carbohydrates into protein: a pound of sugar yields half a pound of fungal biomass, beating mammals and fowl by orders of magnitude.

Working with Aspergillus oryzae, a breed of fungi used in producing miso and soy sauce, Bethencourt and Shigeta brewed their first vats of mycoprotein in Shigeta's basement and processed them into kibble. "They tasted great," says Bethencourt, who used himself as a guinea pig. "I basically would eat a ton of them to make sure they didn't give me diarrhea." (They didn't.)

Backed by $4 million in venture capital, Wild Earth came out of stealth mode in March and announced its dog food will be available later this year. Initially, it will have a price point comparable to premium brands, but the high efficiency of fungi means the price should come down rapidly as the company scales production, Bethencourt says.

Making cat food will take longer. Unlike dogs, cats are obligate carnivores, meaning they must eat meat. Deprived of it, they quickly develop medical conditions from a lack of essential amino acids. Bethencourt and Shigeta figured they could use cell cultures to grow meat without slaughtering any cows or chickens--but why rely on those animals at all? After all, humans raise the livestock we do because the animals in question tolerate captivity and quickly yield large quantities of muscle and fat. But if you're just growing cells in a bioreactor, those considerations don't matter.

Hence the question: If cats could eat anything, what would they choose?

The answer was obvious: mice.

And not just obvious but convenient, since there's no mammal (or bird or fish) whose cells biologists have more experience manipulating than those of the mouse. "What made sense from an R&D perspective, in terms of our understanding of mouse stem cells, made total sense from a product perspective if you realize our customers are cats," Bethencourt says.

Sometime in 2019, Wild Earth plans to begin prototyping its cultured-mouse-meat product and delivering it to its first customers. By that point, Bethencourt hopes, even industrial pet food makers will have realized they need to reform some of their worst practices. "We expect this is going to catalyze the same changes we've seen in the human food industry," he says, referring to trends like the rise of alternative protein, a category whose growth made it one of Inc.'s Best Industries for 2018.

"You can feed your pets without meat. I want that conversation to begin."