Coronavirus

SARS-CoV-2 infection among domestic animals

There is no evidence that domestic animals are playing a role in the spread of SARS-CoV-2, whose predominant route of transmission is from human to human. However, veterinary surveillance and experimental studies suggest that domestic animals can occasionally be susceptible to SARS-CoV-2, so it is important to protect the pets of COVID-19 patients limiting their exposure to the virus.

After leaving its potential wild animal reservoir, SARS-CoV-2 has quickly spread to all continents as the human species proved to be a receptive population, allowing effective intra-species transmission. The virus is now widely distributed among humans and, in some cases, seems to affect also the animals that share their lives and homes. As at 2 April 2020, 800,000 human cases of COVID-19 have been confirmed worldwide, compared to only 4 cases of pets testing positive for SARS-CoV-2: two dogs and one cat in Hong Kong and one cat in Belgium. All of these animals are believed to have been infected by their owners, who had COVID-19.

Despite their limited number, these cases of naturally-occurring infection deserve our attention, considering that also experimental laboratory studies seem to confirm the susceptibility of some domestic animal species, like cats, ferrets and to a lesser extent dogs, to SARS-CoV-2 infection.

The available evidence suggests that exposure to SARS-CoV-2 can cause an asymptomatic/paucisymptomatic infection in animals, and therefore an illness. Infection was asymptomatic in the two dogs and the cat in Hong Kong. The cat in Belgium, however, developed respiratory and gastrointestinal symptoms one week after its owner returned from Italy. The animal displayed anorexia, vomiting, diarrhoea, breathing difficulties and cough, but its symptoms started improving on their own nine days after the onset of the disease. In its report, the Scientific Committee established at Belgium’s Federal Agency for the Safety of the Food Chain informed that high viral loads had been detected in the animal’s faeces and vomit. This finding, combined with the clinical symptoms, suggests that the animal, after being infected by its owner, developed a productive viral infection, that is an infection accompanied by active replication of the virus. It is important to stress that, in all of the 4 reported cases, molecular diagnostic tests were performed and no virus isolation data are currently available to determine the state of infection with greater certainty. Positive serological tests, however, support the hypothesis that one of the two dogs in Hong Kong was infected with SARS-CoV-2.

SARS-CoV-2 is a new virus, so more efforts are needed to detect further signs of potential illness in our pets, without raising unjustified alarm. With the virus now widely distributed and circulating among their owners, domestic animals might occasionally become infected. In the reported cases, however, the animals were only unwitting “victims”.

Indeed, there is no evidence that cats or dogs are playing a role in the spread of the SARS-CoV-2 epidemic, whose main route of transmission is from human to human. However, the fact that domestic animals can become infected raises questions of how to manage the health of animals whose owners are sick with COVID-19. The standard recommendation is to take measures that help reduce their exposure to the virus as much as possible, for example ensuring that the infected owner limit contact with the animal, as they do with other members of their household. The international organizations that have been considering this issue recommend people to avoid petting and kissing animals and implement basic hygiene measures, including hand washing before and after being in contact with animals, their food or litter/bedding. 

It is also important to stress that pets contribute to our happiness and well-being, especially in times of stress like the one we are going through. As long as we don’t have symptoms indicative of COVID-19 and we are not self-isolating in our homes, spending time with our pets and walking our dogs (in compliance with existing regulations) is beneficial for our health and that of our animals.

It is important to remember that our knowledge of SARS-CoV-2 is evolving rapidly, and the information above may be subject to revision. However, the Istituto Superiore di Sanità (ISS) deems it useful to promote the exchange of knowledge, as this knowledge becomes available, to ensure the well-being of both pets and their owners. Therefore, the ISS will be publishing all the necessary updates to present the most recent developments in both the scientific literature and the official positions of the main national and international authorities, and to provide detailed information and guidance.