In 1976, the New York Times solemnly warned that the “Urban Dog Population Is a Rising Problem” in metropolises like Chicago, which is now considered one of the nation’s best cities for dogs. As humans flock to population centers with their animals in tow, some form of the dog poop problem is inevitable. It is not only disgusting and prolific — dogs in the United States produce 21.2 billion pounds of poop annually — but also harmful to our health and environment. To calm the angry masses, San Francisco assembled its own poop patrol. Elsewhere, cities like New York have instituted, to varying degrees of success, pooper scooper laws that more or less command citizens to be good neighbors. None of these measures have stymied the bad behavior.

Enter PooPrints in 2009 and Mr. Dog Poop in 2015.

PooPrints is an offshoot of BioPet Laboratories, which calls itself an animal genetics company and offers proof of parentage testing for canines and cattle. According to J. Retinger, CEO of BioPet Laboratories, PooPrints was borne out of scientist Chesleigh Fields’ frustration with “dog poop everywhere” at her apartment. Nearly a decade later, PooPrints claims to be a multimillion-dollar company and to have generated $7 million in earnings last year.

Mr. Dog Poop, on the other hand, traces its genesis to The Cyber Web Inc., which describes itself as a Tampa-based internet service provider and web hosting service. Looking to move “out of the virtual world, we wanted something more hands on, more blue collar, like picking up dog poop,” explains Mr. Dog Poop’s website, which contains a section titled “Learning to Hate Dog Poop.” It once envisioned itself as the CODIS (Combined DNA Index System, the FBI’s national forensic database) for dogs, and the company’s founder, Mark Guarino, planned to sell access to law enforcement agencies, which might use it to solve crimes.

“No one signed up for that,” he says.

Both PooPrints and Mr. Dog Poop rely on the same technology, called genotyping, that is used by companies like 23andMe.

The person conducting the sample uses a cheek swab to scrape cells from the inside of the dog’s mouth and mails it to a laboratory in a sealed bag. The companies then extract DNA from those cells and test it for certain distinguishing variants. From that information, they claim to produce a unique canine profile, which is then stored in their databases for future poop matching.

“Our PooPrints program is considered a forensics application,” says Retinger, though outside experts told OneZero that the technology should be treated with skepticism.

The business of gathering poop to incriminate a dog is indeed like amateur CSI. Whoever gets the unfortunate task must lop off a piece of the specimen and drop it into a tube of chemical reagent. (“Don’t waste your waste sample on diarrhea,” PooPrint advises.) Next, PooPrints requires the lucky person to manually shake the tube, whereas Mr. Dog Poop provides a battery-powered agitator to turn it “into a sludge.” The sample is then tucked into a biohazard bag and mailed off for analysis.

But unlike the “gotcha!” scenarios on TV crime shows, a computer doesn’t just spit out a DNA match, instantly identifying the perp. Rather, both companies use random match probability to implicate a specific dog. PooPrints’ Retinger claims the company can match profiles so accurately that it has just a “one in 24 sextillion chance of being wrong.” Cross-contamination, insufficient DNA, or non-canine DNA will generate negative results, the companies add.

Even criminal forensics focused on humans is not a perfect science, however, and evidence such as bite marks, considered in some historic cases to be a smoking gun, is now being challenged by lawyers as unscientific and thus unadmissible in court. Dog poop is similarly sketchy, experts say.

“Any ‘black box’ technology in genetics concerns me,” says Elinor Karlsson, director of the Vertebrate Genomics Group at the Broad Institute, a biomedical and genomic research center of MIT and Harvard.

“It is certainly possible to uniquely identify a dog from poop, but genetic tests on feces can be a little tricky, because the DNA is low-abundance and degraded, and the dog’s DNA will be mixed in with DNA from other sources, such as diet and microbiome,” Karlsson says. “This is why we don’t use poop in any of our work.”

PooPrints and Mr. Dog Poop claim the technology they use is tried-and-true, though both rely on proprietary genotyping panels (the specific genes that are looked at) that are not publicly available. “The actual markers are part of our magic sauce,” Retinger says. Making the panels accessible to outside critique would help to dispel some of these concerns.

“The proprietary info is concerning, because we have no idea [what the sequences are] aligning to,” says Imogene Cancellare, a wildlife conservation biologist with the National Geographic Society. “Will any hound breed that poops on the sidewalk amplify and therefore register as the hound on the second floor?”

PooPrints says it has been accredited by the International Organization for Standardization, a third-party certification body that performed its own sort of peer review. (This accreditation did not particularly impress the scientists OneZero spoke with.) Mr. Dog Poop is equally confident in its accuracy. “I feel like the FBI and all of the forensic labs across the country already validated the technology for us,” says Guarino, referring to the fact that law enforcement uses genotyping.

Scientists not affiliated with either company say that errors can potentially sneak in when poop is contaminated.

“Using poop science as a forensic tool is definitely an option, but I would also be concerned about contamination issues, since dog poop samples would be collected within apartment complexes that potentially contain high densities of dogs,” says Claudia Wultsch, a wildlife biologist and research associate at CUNY Hunter College and the American Museum of Natural History.

“It would be difficult to control for contamination with other dog DNA prior to sample collection,” Wultsch adds.