The dog is believed to belong to a Hong Kong Jockey Club member who has been infected with Covid-19, according to the newspaper. The woman's domestic helper is also infected.
Local news website Dimsum Daily named the woman, who is the only known infected person matching the address cited by Hong Kong authorities. The woman is pictured on Facebook with a Pomeranian.
Authorities said they will closely monitor the dog and collect further samples for testing to confirm whether it had been infected, or whether it was a result of environmental contamination of the dog's mouth and nose.
The dog will only be returned to its owner when the test results come back negative. It is currently the only animal under quarantine at the facility, which will be subject to increased cleansing and disinfection procedures.
The spokesman said infected patients were strongly advised to put their pets under their quarantine. He reminded pet owners to maintain good hygiene and wash their hands thoroughly or use alcohol sanitiser after touching pets.
The news is likely to fuel fears about pets passing on the deadly virus, which has infected more than 82,000 people and killed more than 2800 since emerging in China in December, and is nearing global pandemic status.
Earlier this month, Chinese media reported pet dogs and cats were being thrown from apartment blocks after a rumour that the animals spread the coronavirus.
In Australia, one Sydney vet said there had been a spike in pet owners questioning whether the virus can be transmitted from their animals, with some asking if they should euthanise their pets.
The World Small Animal Veterinary Association earlier this month said it was highly unlikely owners could contract coronavirus from their dog or cat, or that their companion animal could transmit the virus to people or other animals.
"Currently there is no evidence that pets or other domestic animals can be infected with this new coronavirus," the WSAVA's official guidance says.
"Additionally, there is currently no evidence that pets or other domestic animals might be a source of infection to people with the new coronavirus. This is a rapidly evolving situation and information will be updated as it becomes available."