A South Korean research team has confirmed Wednesday that some COVID-19 variants -- delta and omicron -- can be transmitted between dogs. Although there have been many reports on the transmission of the coronavirus from humans to dogs, this is the first study that proves transmission of the virus among dogs.

A joint research team, led by Professor Song Dae-sub of Seoul National University's College of Veterinary Medicine and researcher Yoo Kwang-soo of Jeonbuk National University, unveiled the study confirming the infection and virus transmission of two COVID-19 variants between dogs.

The research team infected a beagle with the delta and omicron variants, introducing the virus through the dog's nose. After 24 hours, they put an uninfected dog in the same cage.

After observing any changes for seven days, researchers did not detect any visible symptoms in both the infected dog and the uninfected dog. They only detected symptoms of viral pneumonia, a common symptom of COVID-19, when they analyzed the tissue of the dogs' lungs. The team also found that proliferative viruses can be spread through dogs’ nasal discharge.

The study suggested that human coronaviruses such as COVID-19 and MERS can be transmitted to other species. The research team suggested that pet vaccinations should be actively considered to prevent animal-to-human infection and the emergence of another variant from pets.

"If infection between species and individuals is repeated, the possibility of another variant increases," said Professor Song, adding, "It is time to consider the use of animal vaccines to prevent the reverse zoonosis of pets."

Reverse zoonosis refers to an infection or disease that is transmissible from humans to animals.

The study was funded by the Korea Centers for Disease Control and Prevention, and the paper was published in Emerging Infected Disorders, a medical journal published by the Centers for Disease Control and Prevention of the United States.