When Marcelo Pena Costa saw a Buzzfeed roundup of fun facts from news stories about eccentric Brazilian musician Zeca Pagodinho, one jumped out at him: whenever Zeca drank too much beer at a shopping mall, he would go to a pet store and buy a dog. (In Brazil, beer is served in malls).

Mr. Costa, owner and creative director of Sao Paulo creative lab Senores, was inspired to bring together two of his clients, pet adoption charity Adote um Focinho and Bamberg, a craft beer he said was looking for an out-of-the-box way to engage with customers.

So in March 2015 Bamberg brewed a batch of "Sem Dono" beer ("Abandoned" beer), with six different labels, each featuring a picture and brief description of an adorable dog hoping to be adopted. According to the beer bottles, Balu is "friendly and always serene" and Nero is "really smart." All six dogs found homes, and visits and donations to the shelter increased, Mr. Costa said.

The campaign garnered 20 million social media impressions, with no paid media. That's unusual in Brazil, where campaigns often come with big media budgets, but a hallmark of Senores.

"And the CEO of Bamberg liked the idea so much that he's turning it into a permanent product," Mr. Costa said. A second batch of Sem Dono beer is coming up, featuring a bigger group of adoptable dogs.

And what about Zeca Pagodinho, who inspired the campaign? Senores sent him a few bottles of Sem Dono beer but the singer couldn't comment publicly because he works for another beer brand.

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Mr. Costa started Senores, described as working at the intersection of storytelling and technology, in 2012 with his partner Fabia Barbieri, after returning to his native Sao Paulo from Europe, where he worked for a number of agencies in London. One of their first projects was Bike da Firma, or company bike, a mobile app that tracks cyclists' activity and rewards them. It became so popular that Ms. Barbieri now runs Bike da Firma as a separate, five-person company.

As Senores grows, Julien Condamines, a Frenchman who worked at Google in Ireland and Brazil for four years, joined earlier this year as business and operations director. And the agency recently moved to a new office "next to Sweden." A video about the move included a map depicting Senores as a small country bordering Sweden, a clever way of announcing the agency's new address next to the Swedish consulate in Sao Paulo's upscale neighborhood Jardins.