Environmental NGO Arcturos decried on Monday attempts to poison the Greek shepherd dogs outside its breading in its facility in northern Greece.
The NGO said one female dog, Fiesta, ate a bait poisoned with pesticide during its morning walk outside the center. The animal received treatment but is still in critical condition.
Arcturos believes the move targeted all the dogs of the program, as employees found at least seven poisoned baits outside the center. It also said mass poisoning has happened before in the same area.
This time, three dogs of a passing shepherd were also poisoned near the centre and a ferret was found dead.
The NGO has filed a lawsuit.
Arcturos started a breeding program of the Greek shepherd dog in 1998 to reduce the damage caused by bears and wolves to the livestock of the region, the NGO says on its website.
The move also aimed to protect the endangered breed.