One of the dogs knocked the 50-year-old to the ground and attacked her as the second Boxer joined in, 24 Heures reported.
The woman was able to take refuge in her car parked nearby. She was later admitted to the CHUV hospital in Lausanne for treatment to her bites.
Police were able to trace the dog walker, who had fled the scene, and to remove the animals.
The 70-year-old, who was known to police for similar incidents in the past, claimed not to be the owner of the dogs.
He is currently appealing against a ban on keeping dogs.
The public prosecutor has opened an inquiry.
In Switzerland all dogs have to be microchipped and attacks have to be reported to the veterinary authorities.
There are over half a million dogs kept in Switzerland. Around 9,500 people have to be treated every year for dog bites.