Human monkeypox virus is spreading in Europe and the USA among individuals who have not travelled to endemic areas.1 On July 23, 2022, monkeypox was declared a Public Health Emergency of International Concern by WHO Director-General Tedros Adhanom Ghebreyesus.2 Human-to-human transmission of monkeypox virus usually occurs through close contact with the lesions, body fluids, and respiratory droplets of infected people or animals.3 The possibility of sexual transmission is being investigated, as the current outbreak appears to be concentrated in men who have sex with men and has been associated with unexpected anal and genital lesions.1,4 Whether domesticated cats and dogs could be a vector for monkeypox virus is unknown. Both samples contained virus of the hMPXV-1 clade, lineage B.1, which has been spreading in non-endemic countries since April, 2022, and, as of Aug 4, 2022, has infected more than 1700 people in France, mostly concentrated in Paris, where the dog first developed symptoms. ...the virus that infected patient 1 and the virus that infected the dog showed 100% sequence homology on the 19·5 kilobase pairs sequenced. Given the dog's skin and mucosal lesions as well as the positive monkeypox virus PCR results from anal and oral swabs, we hypothesise a real canine disease, not a simple carriage of the virus by close contact with humans or airborne transmission (or both).