More pets are being poisoned by marijuana plants and edibles than in the past, and some even die, according to a new study.

The study, which was published Wednesday in the journal PLOS One, surveyed veterinarians in Canada and the United States.

The study found cases of cannabis poisoning occurred most frequently in dogs, but other animals suffered too, including ferrets, cats, iguanas, cockatoos and horses.

The study found most pets recovered, sometimes after 24 to 48 hours in a veterinary hospital, but 16 dogs died after ingesting marijuana.

But study author Jibran Khokhar said it's hard to know if the deaths were related to the cannabis or other ingredients in a cannabis edible, such as chocolate.