Image copyright Schutz & Rettung Zurich

Despite looking for their lost dog for six months, the Ehret-Vath family from near Frankfurt never gave up hope.

Last week, the family of five were thrilled to get a call saying the German Shepherd was alive, having crossed the border from Germany to Switzerland.

Rapunzel the dog was found 400km (250m) away, beside a road near Zurich.

The eight-year-old pet was seriously injured, but is now recovering at an animal hospital.

Two Swiss paramedics were returning to Zurich in the middle of the night when they noticed a large motionless animal on the edge of the motorway.

Thought to have been hit by a car, Rapunzel, now very thin, was suffering from hypothermia and wary of the humans approaching.

Realising they could not wait for an animal ambulance to arrive, the emergency responders provided first aid, blankets and oxygen to the canine before rushing her to the University of Zurich's animal hospital, said a city press release.

She has been treated for fractured bones and internal bleeding.

Her owners, who drove down to see Rapunzel at the weekend, said the dog was skilled at opening doors and escaped during a trip to the local vet on 15 August.

"She had never run away before," owner Jasmin Ehret-Vath told local news source Main-Echo, adding that the dog was usually known to be lazy.

A search operation was launched on social media and the family would rush to remote places if any possible sightings were reported.

"We were always on the move," the mother of three said to Swiss news outlet Blick. "But we were always too late."

The pet is still in a critical condition, according to Ms Ehret-Vath, but the family are hopeful she will return home soon.

As for what Rapunzel the runaway saw and did on her six-month odyssey, that will remain a mystery.