Dogs can be vegans too.

That's the premise of vegan dog food company Wild Earth, whose founder Ryan Bethencourt brought a pair of real dogs to his Shark Tank pitch on Sunday. The Berkeley, California-based company creates sustainable dog treats made with koji protein, a type of fungi used in soy sauce and miso. Despite having no sales and a product that hadn't hit the market yet, Bethencourt asked the Sharks for $550,000 for 5 percent of his business. At a valuation of $11 million, the company proved to be a tough sell.

"When you come in here and ask us for over half a million dollars for 5 percent and I have no proof of this concept whatsoever, how can I invest in that?" Lori Greiner said before opting out.

What none of the Sharks could argue with, however, was Bethencourt's impressive professional background. An accomplished biotech entrepreneur, Bethencourt is also a co-founder of IndieBio, a life science accelerator that has invested in more than 70 early-stage biotech startups. While his vision for a pet food that's healthier for dogs and better for the environment made his presentation impressive, guest Shark and RSE Ventures co-founder Matt Higgins wasn't ready to invest.

"You're probably a genius, but you represent what happens when you jack up that valuation," Higgins said, adding that Wild Earth's "inflated" valuation made the product not investable.

Bethencourt argued that demand exists for a vegan and ethically sourced dog food and noted that Wild Earth had already raised $4 million from investors, including PayPal co-founder Peter Thiel and venture capital firm Felicis Ventures. The previous investment round didn't convince the Sharks, however, that consumers would pay $12.99 for a bag of Wild Earth dog treats--almost twice the cost of comparable conventional dog treats. The company launched its product in October of 2018 and now sells bags for $9.99 online.

Though Mark Cuban wasn't scared away by Wild Earth's valuation, he said he'd only invest under one condition: that Bethencourt promise to focus only on proving the success of his existing products before creating more. Cuban offered $550,000 but asked for 10 percent of the company. With no offers from any of the other Sharks, Bethencourt took the deal without negotiating.