A call for more evidence documenting human-to-dog transmission of monkeypox virus

Sophie Seang and colleagues’ description of human-to-dog transmission of monkeypox virus¹ raised concerns about the role of pets in monkeypox virus transmission, reinforcing recommendations from public health authorities that infected people should avoid contact with animals, isolate exposed pets, and consider removing exposed pets from the homes of immunocompromised people.² For example, the US Centers for Disease Control and Prevention now notes that human-to-dog transmission of monkeypox virus has occurred and that signs in dogs include development of a rash, “which to-date have been located on the abdomen and anus”.²

However, the authors of this Correspondence provided insufficient evidence that the adult dog was infected with monkeypox virus: monkeypox virus was detected using PCR in scrapings from the dog's skin lesions and from swabs from its anus and oral cavity, but whether specimens were pooled or tested separately is not stated, and cycle threshold values were not provided to quantify the DNA present. The idea that this was contaminating DNA therefore remains plausible. The lesion on the dog's abdomen resembled a papule seen with bacterial folliculitis, and the anal lesion was barely perceptible. Biopsy proof that these lesions were pox lesions was absent, and there was no serological support for infection. In experimental infections of rabbits, mice, rats, guinea pigs, and hamsters, generalised skin lesions were documented only in rabbits, and adults were more resistant to disease than neonates.³

Although precautions are warranted until we know more, given the staggering implications of human-to-pet transmission, additional studies are required before concluding that dogs are susceptible to monkeypox virus infection and disease.