She was found roaming the streets of Fukushima's exclusion zone, the sprawling ghost town that now surrounds Japan's quake-crippled nuclear reactor. One of an unknown number of dogs that were left chained or abandoned amid the disaster, the haggard-looking mutt bore a scar over one ear and unmistakable signs of chronic stress.

Yuki, as they called her, seemed to be suffering from a canine form of post-traumatic stress disorder.

While some 340,000 people still live as refugees in the wake of the March 11, 2011, earthquake and tsunami, animal science researchers at Azabu University report that former pets have also suffered lingering effects.

In a paper published Thursday in Scientific Reports, lead author and veterinary scientist Miho Nagasawa wrote that stray and abandoned animals recovered near the Fukushima Dai-ichi power station had stress hormone levels far higher than other Japanese dogs.

They also showed greater difficulty learning and developing an attachment to people.