Copper, a tan-and-brown mixed-breed, spent October fighting for his life. The Missouri dog first got sick on October 7, a light cough quickly progressing into a wet hacking one, loss of appetite, and lowered blood oxygen levels. When antibiotics didn’t help, he was admitted to the ICU at his local veterinary hospital.
Copper spent a week in isolation, receiving oxygen support, IV fluids, and antibiotics. Even after returning home, with more antibiotics and an oxygen concentrator to use when he struggled to breath, Copper wasn’t out of the woods. He had to be rushed back to the hospital at one point for another night on oxygen support, and only now is he steadily improving back at home. “We felt close to losing him a few times,” Copper’s owner Kevin Mahoney says.
Over the past few months, the mysterious respiratory illness that almost cost Copper his life has been sickening dogs across the US. Veterinarians don’t know what’s causing it—yet.
Things have been worst in Oregon. The state’s Department of Agriculture began receiving reports of unusual canine respiratory infections back in August. To date, over 200 dogs with a similar illness have been reported in the state, and similar cases have appeared in multiple other states. The disease presents similarly to a bacterial condition known as kennel cough, though symptoms tend to be more severe, last many times longer, and aren’t responsive to the common antibiotics used to treat this known illness. In some cases, the new disease has been fatal.
David Needle, senior veterinary pathologist at the University of New Hampshire, has a lead on what the culprit might be; he thinks it may have been stalking canines for some time. In 2022, Needle’s team began looking at nasal and oral swabs taken from sick dogs in New England, in cases where no known cause of disease was found and the dogs weren’t responsive to treatment. They found a small DNA sequence of a potential disease-causing microbe in 21 of the initial 30 animal samples screened.
Now, in the most recent outbreak, they are screening dogs with long-standing coughs and sneezes from other states that have tested negative for known respiratory diseases—including some dogs from Oregon—to hunt for the same fragment. It’s present in some of the dogs currently sick, suggesting to Needle that the DNA is associated with the emerging illness somehow, but more testing is needed to confirm that the DNA does in fact belong to a pathogen, and what it is. Needle is certain it isn’t a virus—too many genes are present. His best guess is that it’s from an unfamiliar bacteria.
“The thing we found … it seems like it would be something that is really host-adapted and has evolved along with its host for a very long time—like thousands and thousands of years,” Needle says. This understanding is based on the type of bacteria the DNA appears to be from, and how the fragment compares to the genome of the most closely related bacteria, which are highly host-adapted. Furthering this belief is that this suspected bacteria is “not popping up in other animals or people now.” He theorizes that, having long coexisted with dogs, the potential pathogen at some point evolved the ability to cause disease, “either by mutating or acquiring a gene from another bacteria.” He stresses that as what they’ve found is not a previously studied type of bacteria, there is a lot to learn before any concrete answers are available.
Needle believes the increase in this atypical condition now is likely the result of the summer season, when dogs were out in public and interacting. He notes that, in general, seasonal respiratory diseases are not uncommon in domestic dogs. In fact, it’s worth noting that plenty of dogs with atypical respiratory illness that have been recently screened haven’t tested positive for the DNA fragment—suggesting that if it does have something to do with this illness, there may also be other unidentified respiratory pathogens affecting dogs right now.
“To truly prove causation, necropsy submissions of dogs that have died from this disease will also need to be tested, to prove that the organism is present in the diseased areas of lung tissue that are observed,” says Andrea Cantu-Schomus, director of communications for the Oregon Department of Agriculture, which has been working with state and national labs to get samples from the Oregon outbreak sequenced. One of these labs, the Oregon Veterinary Diagnostic Laboratory, has also been assisting in providing a necropsy for dog owners whose dogs appear to have died from this disease and who want this additional diagnostic conducted. But the results of such work are not public.
It isn’t just veterinary researchers who are searching for answers. Owners worried about their dogs’ health have also come together across the country to share resources. At the time of writing, the Facebook group “2023 Canine Infectious Respiratory Disease Tracking” has over 40,000 members, with numbers increasing rapidly. It comprises dog owners and dog professionals, such as dog show competitors, trainers, groomers, walkers, and dog daycare providers from across the country. Members of the group are themselves trying to document and pinpoint locations where dogs are or have been sick and to track any possible spread from popular dog sporting events.
Dog owners are also exchanging advice on the best disinfection products for facilities and sharing what it’s like caring for dogs sick with this suspected syndrome, as well as first-hand accounts of what treatments have and haven’t worked. The idea is that owners of newly infected dogs can pass this information along to their veterinary treatment teams. This informal citizen reporting shows possible cases in over 21 states, although these diagnoses have not been verified by researchers.
Needle encourages dog owners to be patient as a search for the cause of this illness continues. Any kind of vaccine is a long way off, but he hopes this research will help veterinarians in impacted areas better understand how to treat sick dogs—and perhaps even change their treatment approaches.
“The thing we think it might be would not be sensitive to some antibiotics,” he explains, as certain antibiotics only work on bacteria with a particular cell structure. If the researchers can nail down whether it is a bacteria, and exactly what type they are dealing with, they’ll be closer to knowing which medications will be most effective—by eliminating those that definitely won’t work.
Progress is likely to be slow. Compared to research funding for high-priority human respiratory diseases, like Covid-19 or the flu, funding for veterinary research is minimal. Cantu-Schomus adds that this outbreak also highlights the importance of funding state veterinarian offices and diagnostic labs. “While there is no evidence that this disease is affecting any species other than dogs, nearly two-thirds of new or emerging human diseases originate from animals, he explains. “A robust veterinary infrastructure not only protects the health of our animals, but also human public health.”
It’s important to remember that the number of dogs currently known to have been sick is a small percentage of the overall dog population. In addition to watching for signs of infection, which include nasal and/or eye discharge, coughing, and sneezing, dog owners should make sure their dogs are up to date on all vaccines recommended by their veterinarian. These include vaccines for bordetella, canine influenza, and parainfluenza.
Dog owners may also want to consider avoiding large crowds of dogs in places such as dog parks, dog daycares, training classes, and dog shows if they live in an area with reported cases. At the moment, however, there is no official tracker of where the disease appears to be present—only data on the Facebook group or advice from your local veterinarian.
Have a sick dog at home? Needle also notes that if your veterinarian is seeing an uptick in unidentified respiratory disease (suggesting you’re part of an outbreak), you can contact the New Hampshire Veterinary Diagnostic Laboratory. Because the lab is still in the early stages of researching this condition, the more samples they have access to, the better—Needle and his team can get your vet set up to submit samples from impacted dogs if needed.
Caution, not fear, is what’s recommended, Needle says. “Use basic public health practices with your dog” and keep an eye on veterinary news for updates—which hopefully should be forthcoming. “We are a month away from knowing so much more,” he predicts.
