DOVER-FOXCROFT — The animal protection organization Maine Friends of Animals has posted a reward for the arrest and conviction of the person or persons behind a rash of suspected antifreeze poisonings of pets in Piscataquis County.

Since late December, the Piscataquis County Sheriff’s Office has investigated the death of a dog from Parkman and the sickening of a cat and dog from Guilford. Investigator Jamie Kane also probed into the possibility that two more dogs in the Guilford area may have been poisoned, but tests conducted by a veterinarian proved negative for antifreeze poisoning, he said late Wednesday afternoon.

Robert Fisk, executive director of the Falmouth-based Maine Friends of Animals, said Wednesday he is outraged by the apparent poisonings. Maine Friends of Animals is one of the leading animal protection groups in Maine and has been working to help animals since 1997, he said.

“Whoever is doing this needs to be caught as soon as possible,” he said in a statement. “The community is at risk from this very misguided individual.”

Kane said earlier this month he wasn’t sure if someone was intentionally poisoning pets or if it was just a coincidence.

Daryl DeJoy of Penobscot, executive director of the nonprofit Wildlife Alliance of Maine, said last week the pets could have been poisoned by cat food and dog food that had been mixed with antifreeze and left in the woods to kill coyotes.

Kane said the Parkman dog first exhibited signs of disorientation and then lost weight rapidly before it died last month. A local veterinarian who treated the dog for several weeks discovered that it not only had salmonella poisoning, but also suffered from ethylene glycol toxicosis, or antifreeze poisoning.

Police seemed to think it was an isolated case until the same veterinarian told them a few days later he had treated a cat from Guilford that also had exhibited symptoms of antifreeze poisoning. In addition, the veterinarian noted that a Guilford-area dog owner had called him and inquired about symptoms his dog had that were similar, Kane said. The cat, which the vet treated, and the dog both survived.

In 2006, deputies probed the mysterious poisonings of five dogs that became sick and died in the Abbot and Monson region. It was believed then the dogs died from meat that had been poisoned and left in driveways.

“We encourage those with any information to come forward before someone else’s beloved companion animal dies a horrible death from another intentional poisoning,” Fisk said.

Concerned residents can contact Maine Friends of Animals confidentially at 781-2187 or the Piscataquis County Sheriff’s Office at 564-3304 with any information they believe will help identify those responsible for the suspected poisonings.