America is home to many dog lovers, and although they adore their dogs, they often don't love to clean up behind them quite as much. This poses a problem, as dog feces that is not disposed of correctly can get washed into our freshwater systems or leach through soils and contaminate groundwater sources. Dog waste often contains bacteria, some of which are antibiotic-resistant, that can cause people to become ill. Scientists have recently developed a genetic test that will ascertain just how much of the fecal contamination present in our waterways originates from our canine friends.

According to an article that was recently published in the American Chemical Society's journal, Environment Science & Technology, our freshwater systems are vulnerable to contamination from many fecal sources, including leaking sewage systems; agricultural sources, such as waste from livestock and manure added to crops to enrich growth; and wildlife droppings. While these sources all contribute an unsavory source of contamination, dog feces poses a particular concern, as it may harbor antibiotic-resistant strains of bacteria such as E. coli, as well as parasites that pose a public health risk. Considering that the US is home to around 70 million pet dogs, the threat is substantial.

Until now, scientists have had limited resources available to determine how much of the pathogens present in freshwater and coastal systems actually originates from domesticated dogs.

"Current methods look for certain genes from gut bacteria that end up in dog feces", explains Orin Shanks, a co-author of the paper. "However, this is not foolproof — the microbiota of humans and the canine pets they live with often overlap, making the analysis complicated."

To work around this, the research team set about creating a test that would be more specific and robust, and which would be able to detect fecal contamination originating from canines.

By identifying 11 genetic markers that were present in most of the canine samples but absent in the human samples, the scientists developed a genetic technique that is able to test water specifically for the presence of canine fecal contaminants. In order to ascertain whether their genetic technique would be viable for monitoring water quality in a real-world situation, they tested water samples that originated from storm water collected from a rain-garden adjacent to an area that is frequented by dog-lovers walking their canine companions. Using this method the scientists successfully detected the same canine markers they identified in the lab as evidence for canine fecal contamination.

Canine and other sources of fecal contamination in water can contain pathogens that can pose a health risk to you and your family. By filtering your drinking water with a good quality water filter you can successfully remove parasites such as E. coli that could cause you and your loved-ones harm.

Journal Reference:

Hyatt C. Green, Karen M. White, Cathy A. Kelty, and Orin C. Shanks. Development of Rapid Canine Fecal Source Identification PCR-Based Assays. Environ. Sci. Technol., 2014, 48 (19), pp 11453–11461. DOI: 10.1021/es502637b