In 1986, the Chernobyl nuclear power plant in Ukraine experienced one of the worst reactor meltdowns in history, causing residents in the surrounding areas to abandon their homes, leaving behind their pets.

Today, nearly 40 years later, hundreds of stray dogs roam freely within the Chernobyl Exclusion Zone (CEZ), a restricted area spanning approximately 1,000 square miles around the power plant due to radioactive and chemical fallout from the disaster.

These feral dogs, descendants of the abandoned pets, provide valuable information about the impact of contaminated environments on mammals, including humans.

Scientists have recently found that the stray dogs living in Chernobyl’s contaminated environment may have adapted to their surroundings on a genetic level, leading to potential implications for understanding the effects of chemical and radiation exposure on wildlife and humans.

The study, led by North Carolina State University PhD student Megan Dillon, analyzed the DNA of two groups of Chernobyl dogs: one living in the immediate vicinity of the power plant and the other living about 10 miles away in the partially abandoned city.

The researchers observed genetic evidence suggesting that these populations may have adapted to the exposures faced over generations, providing insights into how environmental disasters like the Chernobyl nuclear accident may affect animal populations. The findings were published in Canine Medicine and Genetics.

“Though Chernobyl wildlife has been the subject of previous ecological and genetic studies, little is known about the genetics of a population of over 500 dogs occupying the area surrounding the [Chernobyl Nuclear Power Plant] and Chernobyl City,” said Dillon and her colleagues in the study. “This dog population has expanded in the decades following the accident and is thought to be comprised at least partially of descendants of pets left behind during the chaotic evacuation in 1986.” 

“In this scenario, it is intriguing to understand to what extent the descendants of these abandoned dogs have adapted to survive and sustain a growing population under these extreme environmental conditions,” the team continued. “Understanding and extending the genetic and health impacts of the exposure to both radiological and chemical insults in these dogs will strengthen the broader understanding of how these types of adverse environmental stressors can impact human health.”

Chernobyl’s stray dogs have been the focus of public fascination and scientific curiosity, as they offer a unique opportunity to study the long-term effects of environmental pollutants on ecosystems and human health.

In a recent study, Megan Dillon and her team from North Carolina State University analyzed blood samples from 116 feral dogs, split evenly between the power plant and the city of Chernobyl, to investigate their genetic characteristics.

The samples were collected in 2018 and 2019 as part of a vaccination and sterilization program led by the Clean Futures Fund Dogs of Chernobyl initiative. The findings showed that there was little genetic mixing or interbreeding between the two populations, despite their close proximity.

Although both groups were descended from various domestic breeds, such as the German Shepherd and the West Siberian Laika, they were genetically distinct from each other.

Furthermore, the study provided indications that environmental pressures at Chernobyl could have resulted in certain genetic variations, particularly in genes associated with DNA repair, immune function, and other processes related to exposure to radiation and other pollutants in the CEZ, such as heavy metals, pesticides, and organics.

However, further research is needed to confirm whether these genes do indeed indicate genetic adaptation to the environment over time. Dillon and her team, along with other researchers who have examined these dogs, plan to continue their investigation into the effects of living in a contaminated area.

“As we explore the genomes of the dogs at this location, we aim to identify genome variants that were potentially induced by the prevailing multigenerational exposures and then subjected to ongoing selective pressures to maintain them in the population,” Dillon and her colleagues said in the study. “Our long-term goal with this unique population of dogs is to establish further evidence to evaluate the degree of local adaptation and thus develop measures of the impact of the exposures experienced by these dogs.”

“This work, and future studies with these canine populations, will advance our broader understanding on the genetic effects of prolonged exposures to both radiation and non-radiation toxic exposures, and the findings potentially more broadly applicable to the adverse health effects of other environmental nuclear and non-nuclear disasters in both animal and humans,” the team concluded.