A DNA Dog Fight

Want to track the neighborhood dogs depositing potentially pathogen-laden poop in public places? Two or three scrappy firms will do it with DNA profiling. The big dog in the market seems to be BioPet Vet Lab of Knoxville, Tennessee, with its PooPrints service. It claims to have "eliminated the dog waste problem in 3,000 properties across the U.S." thanks to its "patented DNA World Pet Registry database." [1]

BioPet sued a Dallas, Texas, competitor who had been a local distributor for PooPrints and then established his own brand.  The new company, PoopCSI, boasted that "We are the only firm used by Federal Prosecutors to link Pet DNA from dog feces to convict a man in the home-invasion and rap [sic] of a woman in Texas. The Canine CODIS database in which [sic] we invented is the first multi-agency forensic DNA database of dogs." [2]

Actually, the "Canine CODIS" is not a Dallas creation, but a joint effort involving the more reputable Veterinary Genetics Laboratory of the University of California at Davis to cope with the serious business of dog fighting competitions. [3] VGL Forensics also does DNA testing for law enforcement agencies in cases of animal attacks and when animal DNA "from hair, saliva, blood, urine, or feces [occurs] during the commission of a crime—from the victim's pet to the suspect or crime scene, and from the suspect's pet to the victim or crime scene." [4]

PoopCSI is now called PET CSI. It accuses PooPrints ("dog poop franchise competitors") of "spread[ing] false rumors and produc[ing] fake press releases," having a "fraudulent business model," using "deceptive trade practices," and "theft of pet DNA intellectual property." [5] PET CSI has the worst possible rating (F) from the Better Business Bureau.

There is some irony in PET CSI's stream-of-consciousness complaint that "They are now attempting to lay claim they invented the DNA pet waste matching service when our lab has been doing this it since 1955 and even on their own website they mention they only got started 2008 and only location as early as last year got started." [5] Neither PET CSI nor DNA profiling methods existed in 1955 -- a scant two years after Watson and Crick elucidated the structure of DNA. Human forensic DNA profiling did not begin until at least 30 years later. [6] 1955 might have been the year that the UC-Davis veterinary lab -- which must be "our lab," as indicated by PET CSI's unacknowledged copying of material from VGL's website -- started, under the name of "the Serology Laboratory, ... established ... for the purpose of verifying parentage for cattle registries" using blood typing. [7]

Also nipping at PooPrints' heels is Mr Dog Poop's CRIME LAB. [8] This Tampa, Florida, upstart contrasts its computer database technology as "star trek" compared to PooPrints' "stone-age" methods. Not only does it offer "Dog poop DNA testing [for] $35/dog," but it conducts "Poop And Run DNA Investigations [for] Only $50/incident." After all, "If the FBI can use DNA technology to enforce the law, why can't HOAs, COAs and Property managers?" [9]

This development dismayed one Washington Post writer, who lamented

Yes, it has come to this: We live in a society where, rather than speaking to one another and gingerly asking neighbors to clean up their dogs’ messes, we mail a portion of said messes to Tennessee in a small bottle so that, using genetic sequencing and mathematical logarithms [sic], the canine hooligan can be identified. [10]

Notes

1. The DNA Solution for Pet Waste Management, https://www.pooprints.com/. For varying comments from property managers, see Rick Montgomery, Growing Pet DNA Industry Identifies Poop Offenders, Kansas City Star, May 1, 2014, http://www.kansascity.com/news/local/article348234/Growing-pet-DNA-industry-identifies-poop-offenders.html; PooPrints is [sic] Fabricated its Pet Waste Business Nationwide, Ripoff Report, Apr. 30, 2015, https://www.ripoffreport.com/reports/pooprints/nationwide/pooprints-is-fabricated-its-pet-waste-business-nationwide-1225902.
2. Eric Nicholson,Two Companies, PooPrints and PoopCSI, Are Battling for the Right to DNA Test Dallas' Dog Crap, Dallas Observer, Aug. 20, 2013, http://www.dallasobserver.com/news/two-companies-pooprints-and-poopcsi-are-battling-for-the-right-to-dna-test-dallas-dog-crap-7102482.
3. University of California at Davis Veterinary Genetics Laboratory, Canine CODIS: Using a CODIS (Combined DNA Index System) to Fight Dog Fighting, https://www.vgl.ucdavis.edu/forensics/CANINECODIS.php.
4. University of California at Davis Veterinary Genetics Laboratory, VGL Forensics, 2018, https://www.vgl.ucdavis.edu/forensics/index.php.
5. PET CSI® Difference, 2018, http://www.petcsi.com/pet-csi-difference.
6. David H. Kaye, The Double Helix and the Law of Evidence (2010).
7. University of California at Davis Veterinary Genetics Laboratory, About the Veterinary Genetics Laboratory, 2018, https://www.vgl.ucdavis.edu/vgl/about.php.
8. Compare DNA Dog Poop Services, http://mrdogpoop.com/splash/compare.html.
9. What Is Mr Dog Poop's® CRIME LAB® Dog Poop DNA Service?, http://mrdogpoop.com.
10. Karen Heller, Using DNA to Catch Canine Culprits — and Their Owners, Wash. Post, Dec. 26, 2014, available at https://www.washingtonpost.com/lifestyle/style/using-dna-to-catch-canine-culprits--and-their-owners/2014/12/26/8d833fc8-8247-11e4-8882-03cf08410beb_story.html?utm_term=.7c49e9dc734a.

Related Postings

• Canine DNA Databases to the Rescue, Apr. 17, 2011
• Adopted Family Members Placed Under Genetic Surveillance, July 3, 2011
• A Probability for Dog DNA, Jan. 14, 2015

Related News Stories

• Debra Cassens Weiss, Lawyer Says Condo’s Proposed PooPrints DNA Program Is ‘Absolutely Ridiculous,' ABAJ, May 20, 2010, http://www.abajournal.com/news/article/lawyer_says_condos_suggested_pooprints_dna_program_is_absolutely_ridiculous/
• Stanley Coren, CSI Meets Dog Poop, Psychology Today,  June 30, 2011, https://www.psychologytoday.com/blog/canine-corner/201106/csi-meets-dog-poop.
• Danny Lewis, Dog Owners Beware, DNA in Dog Poop Could Be Used to Track You Down, Smithsonian Mag., Mar. 30, 2016, https://www.smithsonianmag.com/smart-news/dog-owners-beware-dna-dog-poop-could-used-track-you-down-180958596/
• Maria Arcega-Dunn, City Uses DNA to Track Dog Owners Who Don’t Pick Up, Fox 5 (San Diego), Apr. 29, 2015, http://fox5sandiego.com/2015/04/29/san-diego-turns-to-dna-to-trace-dog-owners-who-dont-pick-up/
• 7NEWS, Colorado Dog Owners Fined Hundreds After Not Picking Up Pet Poop, Denver Post, Nov. 10, 2015, https://www.denverpost.com/2015/11/10/colorado-dog-owners-fined-hundreds-after-not-picking-up-pet-poop/
• Eli Pace, Breckenridge Weighs DNA Testing Dog Poop After Complaints Pile Up, Summit Daily, Mar. 5, 2018, https://www.summitdaily.com/news/breckenridge-weighs-dna-testing-dog-poop-after-complaints-pile-up/

A Probability for Dog DNA

A pet peeve of many statisticians is the transposition fallacy—misconstruing the probability of the data given the hypothesis as the probability of the hypothesis given the data. In general,

P(data | hyp) ≠ P(hyp | data).

The term “pet” is particularly apt in the case of yesterday’s PBS “Here and Now” interview on animal DNA analysis in forensic science. The program’s host interviewed WBUR’s Vicki Croke, who has written an engaging and informative account of “Pet CSI: How Dog and Cat DNA Nabs Bad Guys.” She begins with the following case:

On Sept. 14, 2000, Wayne Shumaker, 58, Corby Myer, 30, and Lynn Ganger, 54—three carpenters building a barn loft at an upscale property near Lakeville, Indiana—were bound and shot execution style during an armed robbery. Less than two years later, the triggerman in the case, Phillip Stroud, was found guilty on all three counts of murder and sentenced to life in prison. The criminal was done in—at least in part—by the dog droppings he had stepped in during the commission of the crime. It turns out that dog feces not only messed up his sneakers, but his defense too. It was a simple mistake that was exploited by the prosecution using some new and very sophisticated science. Samples from Stroud’s sneakers were compared to dog feces at the barn. Through DNA analysis (as they exit, feces snag DNA-carrying epithelial cells from the colon), the specimens turned out to be a perfect match—proof positive that the defendant had been present at the scene of the crime.

In the interview, Ms. Croke elaborated on "proof positive" as follows:

[T]he lab needs to calculate probabilities. How common is this particular pattern of DNA in the wider population? In other words, how likely is it that this hair could have come from any other dog or cat than the one linking the criminal to the crime? In the triple murder case we were talking about, the probability that the feces on the suspect’s sneaker came from any other dog than the one at the scene of the crime was one in ten billion!

Here and Now's webpage thus refers to "a probability test to determine how likely it is that the DNA comes from any other animal in the area."

These characterizations are fairly typical examples of transposition. The data in the triple-murder case are the pair of DNA profiles that are said to match. The hypothesis is that the source of the sneaker DNA is a different dog. We’ll call this the defense hypothesis, def-hyp. Assuming no laboratory error in profiling ever occurs, the probability of the data—the matching profiles—given that they came from different (and unrelated) dogs is the frequency of the profile in the “wider population.” Let’s assume that one in ten billion is a good estimate of that probability. That is,

P(data | def-hyp) = 1/10,000,000,000.

Is “the probability that the [DNA] came from any of other dog” also 1/10,000,000,000? Not exactly. This probability is P(def-hyp | data). According to Bayes' rule, it depends not only on P(data | def-hyp), but also on two additional probabilities. For one thing, we need to know the probability of the data given the prosecution’s hypothesis, P(data | pros-hyp). This probability is 1 (if the lab is certain to declare a match when the two samples really contain the same dog's DNA).

Another factor to consider is the prior probability of the defense hypothesis, P(def-hyp). How many alternative dogs could have been crossing defendant’s paths in the weeks before the murder? One thousand seems like a lot. If we take the prior odds for the defense hypothesis to be 1,000:1, then the match to the dog doodoo in the barn reduces these odds to 1,000:10,000,000,000 = 1:10,000,000.

What is the moral? Transposition is wrong, but almost everybody, from journalists to jurors, does it. A DNA match to a random, unrelated dog may be a one in ten-billion event, but it does not follow that the probability that defendant stepped on stuff from an unrelated dog is one is ten billion. That said, if the random-match probability is as infinitesimal as one in ten billion, the probability of the defense hypothesis (about an unrelated dog being the source of a true match) is still doggone small. Transposition should be avoided, but it is not always the most grievous of errors.

Adopted Family Members Placed Under Genetic Surveillance

OK, the title is misleading, but here's the poop. About two dozen apartment complexes around the country have signed up to have DNA from canine residents entered into a "worldwide database" known as "PooPrints." The apartment manager can send in a swab for DNA profiling and databasing. Then, when renters fail to clean up after their pets, they can send the evidence sample to the Knoxville company, BioPet Vet Lab. [1]

Plainly, this is a niche market. Orchid-Cellmark, a bigger player in the private DNA typing market, won't touch samples of feces.

PooPrints is not the first database to contain profiles from innocent and guilty dogs alike. The picturesque Italian isle of Capri planned a database to help keep it narrow walkways clean. [2] The city of Petah Tikva, near Tel Aviv, took a more positive approach, testing special trash cans in a poop-filled neighborhood and giving the owners a small reward for database hits. [3] Port Phillip, Australia, relied on a voluntary DNA repository in 1998--along with "other evidence such as eyewitness accounts, photographs and video surveillance." [4]

In a more serious vein, a thoughtful review of issues in forensic DNA identification in which dogs are a source of evidence can be found in the latest issue of the Croatian Madical Journal. [5]

References

1. Katie Zezima, Tracing Unscooped Dog Waste Back to the Culprit, with Science, New York Times, July 2, 2011, at A10

2. Capri to Set Up 'CSI-style' DNA Database to Catch Owners Who Refuse to Clean up Dog's Mess, Daily Mail Reporter, Mail Online, April 11, 2011

3. Rebecca Skloot, Dog-poop DNA Bank, N.Y. Times Mag., Dec. 12, 2008

4. Australians Scoop Up Dog DNA, Ariz. Republic, Sept. 26, 1998, at A27.

5. Gunther Scharnhorst & Sree Kanthaswarny, An Assessment of Scientific and Technical Aspects of Canine Forensics DNA, Croatian Medical Journal, 2011, 52: 280-92

Cross-posted from the Double Helix Law Blog.

Canine DNA Databases to the Rescue

There have been proposals to slowly create a population-wide DNA identification database by having medical workers submit to a centralized, law enforcement database an identifying DNA profile from the blood samples used to screen every newborn for genetic diseases.

According to the Daily Mail, the Italian island of Capri is implementing a similar plan -- for the island's population of 1,000 resident dogs. Some of these animals soil the picturesque, white-washed alleyways on the Mediterranean island. So the mayor is taking advantage of a law requiring dogs to have bloodtests for canine leishmaniasis, a disease transmitted by sandflies, to build a database. Then, samples of any dog mess found on the pavements in the popular holiday island will be sent to a crime laboratory for testing to identify the offending dog and its owner.

Capri is not the first city to plan a local canine database. In 2008, the New York Times reported that the mayor of Petah Tikva, near Tel Aviv, "recruited a small army of 12-year-olds from a local grade school [who] went door to door, persuading dog owners to donate samples and explaining the drawbacks of poop (worms, bacteria, general grossness)." She also "began collecting samples as part of annual pet exams and organized a DNA-donating festival featuring music, performing dogs and a booth for saliva collection." About 90 percent of owners agreed to donate samples when asked.

The project was about more than waste elimination: “We can use this DNA database for important things like genetic research on dog diseases,” the mayor said. “We could also use DNA to identify strays and return them to their parents.”

References

Daily Mail Reporter, Capri to Set Up 'CSI-style' DNA Database to Catch Owners Who Refuse to Clean Up Dog's Mess, Daily Mail Online, 11th April 2011.

Rebecca Skloot, Dog-poop DNA Bank, The, N.Y. Times Mag., Dec. 12, 2008

(Cross-posted from the Double Helix Law blog)