"The hunter had set his rifle against a tree and went to collect a woodcock he had just shot," the mayor of Mesplede, Regis Cassaroume, told AFP.
Police said the dog apparently knocked the rifle over and managed to trigger the weapon by stepping on it.
Local media reported that the dog had been extremely agitated at the time and had repeatedly jumped on the gun, perhaps excited at the fact his master had successfully shot the bird.
The hunter, a 61-year-old pensioner, received treatment at a nearby hospital for wounds to a hand and forearm.
While the hunter was lucky to get away without more serious injuries, there have been a slew of hunting accidents in France since the hunting season began in September.
In October, a walker wearing brown clothes was killed after he was accidentally shot dead by a hunter who mistook him for a deer.
Last year's hunting season claimed the lives of 16 people, many of whom were hunters too.
This year's hunting season closes at the end of February.