The Pack (1977 film)

The Pack is a 1977 horror film about a pack of abandoned dogs who turn against humans by killing them for food at Seal Island.

Meanwhile, a boy and his parents, the last of the summer tourists, feel forced to leave their dog behind because they knew that they would be forced to send him back to the dog pound. Later that day, he is found by a pack of feral dogs, most of whom were abandoned pets belonging to summer tourists. Their leader, a massive goldenhaired mongrel, immediately accepts the dog into his pack.Jerry Joe Don Baker has moved to Seal Island with his new wife, Millie Hope AlexanderWillis, and their two sons. They also brought along their family dog, a German Shepherd named Riley. While dropping off some garbage at the island junkyard, Jerrys dog chases after a rabbit into the trees, but is attacked by an unknown creature and is injured. When Jerry goes back to see what it was that attacked Riley, he discovered that it was a feral dog, who had apparently also stole the rabbit that his dog was chasing. He immediately sent word to the other residents on the island, including the old hermit Mr. McMinnimee Delos V. Smith Jr., to keep a watchful eye out for the dog and kill it if they ever see it again. ........

Source: Wikipedia