According to a research report released on August 10, 2022, a dog in Paris contracted monkeypox from one of its owners, both of whom were sick with the virus. This is the first instance of a dog catching the monkeypox virus from skin sores on a human.

I am a veterinary pathologist and virologist with over 20 years of experience working with poxviruses. I am investigating how these viruses avoid detection by the immune system and am focusing on manipulating poxviruses to prevent infection as well as cure other diseases such as cancer.

With monkeypox growing in humans worldwide, my colleagues and I have begun to be concerned about the increased possibility of monkeypox transmitting from humans to animals. If monkeypox spreads to animals in the United States and Europe, the virus might become endemic in these areas, where it has hitherto been absent, leading to more regular outbreaks. According to the account of the diseased dog, there is a good likelihood that these concerns may come true.

Monkeypox is a poxvirus of the same family as variola (the virus that causes smallpox) and cowpox viruses, and it most likely originated in animals before making its way to humans. Monkeypox produces painful sores in both people and animals and can be fatal in rare situations. The monkeypox virus has been discovered in various species of wild rodents, squirrels, and primates in Africa, where the virus is endemic. Monkeypox does not need to change or evolve in order to infect a wide range of species. It is easily transmitted from animals to humans and back again.

Though monkeypox has received some attention, cowpox, a related zoonotic poxvirus that is widespread in Europe, has received far more attention. Several cases of cowpox infection spreading from animals to people have been reported in Europe over the years.

Until recently, the majority of monkeypox infections occurred in certain parts of Africa, where certain animal species functioned as viral reservoirs. These epidemics are typically managed quickly by isolating infected individuals and immunizing those in close proximity to the afflicted individual.However, the current scenario is rather different.

Monkeypox is now common in the human population, with approximately 40,000 cases worldwide as of Aug. 17, 2022 — and more than 12,500 cases in the United States alone. The likelihood of a single human passing the virus to an animal, especially a wild one, is low, but the more individuals who are infected, the higher the odds. It’s all about the statistics.

Viruses may spread from animals to humans in a variety of ways, known as spillover, and from humans to animals in a process known as spillback. Monkeypox is more difficult to transfer between species than COVID-19 because it is most commonly disseminated through direct skin-to-skin contact.

The story of the dog in Paris exemplifies how snuggling or being around a pet might transfer the infection. Previous research on poxviruses, such as monkeypox, has demonstrated that they may survive in feces. This implies that wild animals, most likely rats, are in danger of contracting it through human feces.

The monkeypox virus can also be found in saliva. While additional study is needed, it is feasible that an infected person may throw away food that a rodent would consume.

The likelihood of any of these events occurring is exceedingly low. However, I and other virologists are concerned that if more humans become sick, there is a greater potential that rats or other animals may come into contact with virus-infected urine, feces, or saliva.

Finally, there is the potential that people will infect a pet with monkeypox, which will then infect other animals. In one case study in Germany, an epidemic of cowpox was generated when someone brought an infected cat to a veterinary clinic, and four additional cats became sick as a result. It is possible that an infected home pet might inadvertently transfer the virus to wild animals.