“It’s rodents that scare me,” she said.

If the virus becomes established in wild animals like rats or squirrels, eradicating it becomes exponentially harder. Rather than being limited to humans, it would take up residence in countless tiny vectors that in turn could infect other animals, pets and people.

Miller said she feels “horrible” for the greyhound, “but there are clear protocol on how to manage infected pets. … I would only worry about it with spillover to rodents.”

She is not alone.

The prospect of monkeypox becoming endemic in rodents — an order of mammals notorious for their hardiness, mobility and effectiveness at spreading pathogens — is “the thing that keeps me up at night,” said Anne Rimoin, a UCLA epidemiologist who has studied it for the last two decades.