A woman in Stanley was taken to hospital with serious injuries after being attacked by her dog on Thursday around noon.
The New Brunswick SPCA were called in to assist the RCMP, but the dog had already been put down by another owner by the time they arrived, said chief animal protection officer Denise Potvin.
The dog, a large mixed breed, will be tested for rabies because of reports it was acting strangely, she said.
"The dog is deceased and we have the option — I think we'd be crazy not to," said Potvin.
"I'm not a doctor, but the girl — the owner of the dog — that was attacked, if we find that the dog has rabies, then it's really important that she get medical care."
The virus can be lethal for animals and humans, if not treated right away.
Most people who show symptoms of rabies don't survive. Those who do usually suffer severe neurological damage.
Humans can be vaccinated against rabies before exposure to the virus. They are also vaccinated after contact, although immunization is recommended as soon as possible after exposure.
The necropsy could be performed as soon as Friday, said Potvin.
The last reported case of rabies in New Brunswick was in a cat in Balmoral shortly before Christmas. It was the first confirmed case of feline rabies in more than a decade.
Since 2001, rabies cases in New Brunswick have also been reported in raccoons, bats, skunks and a horse.