A dog in France has been diagnosed with monkeypox, the first human disease to be transmitted to animals.
The Lancet published the study after a four-year-old Italian grizzly bear was found after living with two men in France.
The dog had no previous history, but 12 days later the man had stomach ulcers. Dog friend avoids people and other animals, but he sleeps in his bed.
DNA tests show that humans and dogs have the same type of Monkeypox.
The researchers wrote that "Our results should stimulate discussion about the need to isolate animals from humans with monovirus."
The Centers for Disease Control and Prevention has updated its pet guidelines after reports that dogs may be infected. Meanwhile, pets around people with flu symptoms should stay away from people and other pets for 21 days, the CDC said.
"Infected animals should not be treated," the agency said. "People with rubella should avoid close contact with sick animals, and if possible, ask other family members to take care of the animal until the rubella is cured."
Health officials hope the report will provide new guidance on what to do if people contract smallpox, but it is unclear whether dogs can transmit the disease to humans, animals or people.
Monkeypox is common among gay men and lesbians, and the virus is often spread through close contact. There are 11,890 confirmed cases in the US