One of the deadliest Covid-19 variants can be transmitted between dogs, scientists find

Infected and virus-naive dogs kept in animal isolators for a week to check transmission

Certain variants of Covid-19, including the severe Delta, can be transmissible between dogs, a study by a South Korean research team has found more than two years after the pandemic crippled the world.

The SARS-CoV-2 pandemic has been driven mainly by human-to-human transmission, however, zoonotic viral infections from animals to humans have been reported worldwide.

The joint study led by professor Song Dae-sub of Seoul National University’s College of Veterinary Medicine and researcher Yoo Kwang-soo of Jeonbuk National University, is the first that found transmission among dogs.

The team infected Beagle dogs with the Delta and Omicron variants of the virus by introducing it through their noses.

A study by India's Centre for Cellular and Molecular Biology last year found that while Omicron is one of the most contagious variants of the virus yet to emerge, Delta is among the most deadly. The team found that human immune systems could not produce the molecules required to defend against Delhi as effectively as with other variants.

After 24 hours, the infected dogs were kept with virus-naive dogs in large animal isolators.

The researchers couldn't detect any visible symptoms in either of the infected and virus-naive dogs after observing them for over a week.

After 10 days of cohousing, the lung tissue of the dogs was collected for histopathologic examination and viral load measurement. An analysis of the lungs showed microscopic lesions were in both the infected and transmission canines.

"Among the blood chemistry parameters, creatine kinase levels were markedly increased in Omicron-infected dogs," the study found.

It also found that proliferative viruses can be spread through dogs’ nasal discharge.

"Our results demonstrate that the dogs were susceptible to infection with and could transmit both strains to other dogs through direct contact," the study found.

According to the study, Sars-CoV-2 or Middle East respiratory syndrome (Mers-CoV) can be transmitted to other species. The research team has suggested that pet vaccinations should be actively considered to prevent animal-to-human infection.

“If infection between species and individuals is repeated, the possibility of another variant increases,” professor Song was quoted by the Korean Herald as saying.

“It is time to consider the use of animal vaccines to prevent the reverse zoonosis of pets.”

The early release of the study, funded by the Korea Centres for Disease Control and Prevention, was published by the United States Centre for Disease Control and Prevention.