Pets get ill. Sometimes, outbreaks of pet illnesses occur—but there is no Centers for Disease Control and Prevention (CDC) for pet diseases. Owners decide whether to get their pets tested, and in most countries, there is no mechanism for veterinarians to formally notify one another nor a state body that tracks disease trends.
Moreover, surveillance of pets for new viruses or new variants is not routine. Veterinary scientists in the UK and the US are trying to change that with twin initiatives aimed at monitoring pet populations for outbreaks. Their aim is to alert vets about new microbial threats to animals, but some infectious disease researchers say such monitoring might one day also serve as early warning systems, detecting pathogens that threaten to spill over into people.
For many virologists, this fills a clear gap. “There is not a country on the planet that I’m aware of that has a national surveillance system for [general] cat and dog diseases. I think that’s a blind spot,” says Alan Radford, a veterinary virologist at the University of Liverpool. In the UK, unlike with human patients, there’s no public funding for diagnostic tests of pets, and little money or incentive to collect data that would provide a nationwide picture of pet diseases or health status. “There is no Public Health England for dogs,” quips Radford. “So that generally for companion animals, that ability to have a national view of disease is not present.”
Currently, says virologist Gerald Barry at University College Dublin, Ireland, vets often swap information informally, such as by contacting colleagues or posting on social media if they see something unusual. This can alert vets to, for example, test for a specific microbe or fine-tune their prescribing practices.
But it is difficult to separate the coincidental from a trend without proper monitoring records. Radford with colleagues addressed that need in 2008 by setting up arguably the first surveillance network for small animals: the Small Animal Veterinary Surveillance Network (SAVSNET). This collects data from vets and from commercial diagnostic labs from across the UK for the purposes of research and surveillance. It has been a slow process to set up the network, with no obvious funding bodies to turn to. “It has taken us a lot of hard work to get us to where we are today,” says Radford.
The dream: real-time forecasting of outbreaks
The network proved its worth following a phone call Radford received from vet Danielle Greenberg, who thought she was seeing more cases than usual of severe vomiting in dogs in the Liverpool area in January 2020. She wanted to know if this was a true outbreak and if other people were seeing it.
SAVSNET analyzed data it had collected from across the UK and found an uptick in gastroenteric disease among dogs—not just in the northwest, but across most of the country. “It was essentially twice the normal level,” says Radford, adding that they also saw a substantial increase in prescribing of drugs used to treat vomiting.
Further statistical analysis confirmed that this was unusual, matching the definition of an outbreak. The SAVSNET team made its findings public in a report in the CDC’s Emerging Infectious Diseases in February 2021. This revealed that the vomiting outbreak was significantly associated with a canine enteric coronavirus and seemed especially severe around the cities of Edinburgh, Guilford, Swansea, Bristol, and Manchester. Radford and his colleagues set up a website to post live information and advice to vets, to help them manage and isolate cases and to communicate such issues to owners.
Nearly all the dogs that tested positive for canine enteric coronavirus had a single variant, Radford explains, so the suspicion is that a new variant arose or arrived in the UK and rapidly spread through the dog population. Whether the same virus rippled through other countries is unknown. However, in February of this year, newspapers reported a vomiting outbreak among dogs in Ireland, possibly related to the same enteric canine coronavirus.
Radford says he hopes the network in Liverpool will inspire similar enterprises elsewhere. Already, it spurred US vets at the University of Minnesota to set up the Companion Animal Veterinary Surveillance Network, CAVSNET in 2019. CAVSNET seeks to record outbreaks and disease and treatment trends in small animals and horses in a statistically rigorous way. The network collects data from approximately 115 vet clinics across the US so far. It will track disease trends over time, identify animal populations at risk, describe treatment practices and outcomes, and provide data for veterinary research, its organizers say. “This is essentially a sister network to SAVSNET,” explains Jennifer Granick, a veterinary clinician at the University of Minnesota’s Veterinary Medical Center and a senior investigator and cofounder of the network.
Its first project, partly funded by the US Food and Drug Administration, will evaluate antibiotic use for common diseases in cats and dogs. Presently, there are no good estimates of antibiotic use, overuse, and resistance in small animal care. “We can’t make meaningful changes in terms of antibiotic use if we don’t know what our prescribing practices are to start with,” explains Granick. “Tools for measuring antibiotic use in veterinary medicine are rare.” CAVSNET tracks prescriptions by species, clinical syndrome, and drug type.
Granick notes that animals are intimately associated with their owners, often sitting on beds or couches. “There’s a lot of sharing, and that is particularly relevant when we’re talking about resistance to antimicrobials, because we share our microbial communities,” she says. “We also know that multidrug resistant infections can be transmitted from people to pets and vice versa.”
From pets to people
“Animals may also serve as sentinels for disease that can occur in people,” such as Lyme disease or fungal infections, Granick notes. So in the future, she says CAVSNET could track diseases that can pass from animals to humans, and potentially act as an early warning system, as regional upticks in animal cases could signal to public health officials the potential for illness in humans. This fits also into the principle of One Health, an approach that recognizes the importance of the intersections between environment and microbes in people and animals.
Pets could also be sources of novel human pathogens. For instance, while there are no indications that the UK canine coronavirus jumped into people, reports elsewhere suggest that coronaviruses from pets sometimes infect people. A study in Arkansas in 2014 found cat-like coronaviruses in some people with flu-like illnesses. Then, in May of this year, a team of US virologists and Malaysian medics reported in Clinical Infectious Diseases that out of 301 hospitalized pneumonia patients in the Sarawak region of Malaysian Borneo in 2017 and 2018, eight were infected with a canine coronavirus (part of the virus’s spike protein was almost wholly derived from a cat coronavirus, and another part of the spike appeared to come from a pig coronavirus).
“As we’ve seen with coronaviruses now, there’s always the possibility of zoonotic infections jumping from animals to humans,” says Barry. And coronaviruses are not alone. The last flu pandemic in 2009, for example, likely came from the mixing of strains of bird, pig, and human virus in a pig. The Nipah virus in bats sometimes causes deadly infections in people—and can infect pigs—and is still viewed as one of a number of pandemic risks.
While it’s not a bad idea to screen pets, Marco Salemi, a microbiologist at the University of Florida, says “the next potential coronavirus epidemic is more likely to come from wildlife reservoirs.” Surveillance there will be more important to public health, he adds, but surveillance of wildlife, farm animals, and pets should all paint a fuller picture of what pathogens could potentially cause future outbreaks in people.
“There is a lot of talk about One Health,” says Radford. “But the funding doesn’t tend to reach the animal side. Even the surveillance side didn’t get a huge amount of funding before this, but that might change now [due to the pandemic].” The UK network continues to pursue government and philanthropic funding, and is supported by modest income from veterinary pharmaceutical companies.
Barry notes that, “from a One Health point of view, we want make sure that our domestic animals are healthy.” And when it comes to human health, he says, “what the pandemic has told us is that surveillance and identification of potential [zoonotic] risks is the way forward, because we want to be able to identify these things before the problem emerges.”