November 24, 2023

Canine Infectious Disease Outbreak: Winter 2023

Medically reviewed by Bradley J. Waffa, MSPH, DVM
Last Updated: 12/13/2023
If you have a dog, you’ve likely heard some buzz about a mysterious respiratory pathogen that has been spreading around the country. As the Triangle’s premiere veterinary urgent care, we have been getting many calls from concerned pet owners. We are updating this page regularly with the latest information about this disease. If your pet is currently experiencing a cough or other respiratory signs, please call us directly to discuss the most appropriate plan for your pet: 919-981-9881.


Fill me in. What’s going on?

We have been tracking reports of an “atypical” canine infectious respiratory disease described in other states. The bulk of recent reports have come from Oregon where the Oregon Department of Agriculture (ODA) has cited over 200 cases since mid-August, however, an earlier cluster was recognized in New Hampshire and neighboring states last summer, and there has also been a recent possible case cluster in the midwest.


Canine infectious respiratory disease… like Kennel Cough?

Yes, the term “kennel cough” is a popular name for this problem which is technically a syndrome, i.e. a condition characterized by a set of associated symptoms. The technical name is “CIRDC” which stands for “canine infectious respiratory disease complex” (I know, kennel cough is much easier to say!). The word “complex” is an important one though, and refers to the fact that it’s not simply one organism responsible for syndrome, but nearly a dozen possible culprits, with frequently more than one organism involved (this is called coinfection).


Got it. But this CIRDC is “atypical”?

Yes, CIRDC is a syndrome characterized by a highly similar and predictable set of symptoms. This disease of concern though has not been what is typically seen in CIRDC. The disease begins with symptoms that closely resemble those seen in a more typical kennel cough scenario – sneezing, coughing, nasal and ocular discharge – except that, unlike kennel cough (which is typically self-limiting and resolves in 7-10 days), this disease can drag on for 6-8 weeks and seems unresponsive to normal treatments. While the majority of these cases have not been life-threatening, there does seem to be a small subset of otherwise healthy dogs who have become acutely sick with life-threatening pneumonia, and multiple fatalities have been reported.


What do these “atypical” CIRDC cases look like?

The ODA reports that their cases often fall into one of three categories:

  • A chronic, mild nuisance cough with a frustratingly protracted duration (6-8 weeks) that is stubbornly unresponsive to therapy; this is most common
  • A chronic pneumonia that is also minimally responsive or unresponsive to antibiotics
  • Acute pneumonia that rapidly becomes severe and can be fatal within 24-36 hours despite intervention; this is much less common, but obviously most concerning

The categories are not mutually exclusive of each other, and dogs in one category can potentially progress to another.


Yikes. Do we know what’s causing it?

Nope, and that’s sort of the crux of the mystery and concern right now: while CIRDC can be caused by nearly a dozen different organisms (or combinations thereof), most of these atypically sick dogs that have been tested are reportedly negative for all of the usual suspects.


So we’re testing all these coughing dogs and not getting answers?

Well, sort of. For one, we generally don’t test every coughing dog. The expense aside, testing is not even usually indicated for mild cases of CIRDC because a presumptive diagnosis can be established based on clinical history, symptoms, and a physical exam. It wouldn’t make any more sense than hunting for which particular virus is responsible for all the runny noses in a daycare. There is just always a “base rate” of CIRDC circulating in the dog population at any given time, just like the common cold (which is also caused by a handful of different viruses) circulates in the human population. Occasional outbreaks are expected, with the causative agent(s) frequently unidentified, and they usually disappear as randomly as they begin.

Of course that changes in an epidemic scenario. In light of recent events, more severe cases of CIRDC are being tested, and in these atypical cases that have been reported around the country, many have been negative.


Is this like COVID-19 for dogs then?

Well, that has certainly been everyone’s concern, though fortunately, it does not seem to be playing out that way (and incidentally, researchers at both Colorado State and the New Hampshire Veterinary Diagnostics Laboratory have tested their recent CIRDC cases for SARS-COV-2 and all have been negative – so, no, it is literally not COVID!)

Why this disease has been so challenging to identify is an active point of discussion in veterinary infectious disease circles.

Yes, one obvious concern is for an entirely new pathogen to add to the “complex” of organisms involved in CIRDC. That, in the same way COVID wreaked havoc on humans, some completely novel organism is quietly sweeping through the population of our beloved canine companions. One epidemiologic feature of truly novel pathogens though is that they’re generally not quiet. Rather, we see a steep, rapid, and sustained increase in case counts (as we saw in COVID, incidentally). Granted there’s no centralized disease database for pets, so the data we actually have is frustratingly fragmented and incomplete. But from what’s been documented so far (e.g. regional data from pet insurers like Trupanion) that doesn’t seem to be the case. We’ve also seen a precipitous decline in the volume of respiratory cases in the weeks following Thanksgiving, a pattern more in line with a typical “flash in the pan” outbreak of CIRDC. Now this could all mean we’re dealing with a novel pathogen that simply isn’t highly transmissible, or that the mitigating efforts of concerned pet parents have helped to blunt the type of case volume we might normally see – it’s probably still too early to say – but the limited case volume we’re currently seeing is encouraging.

There are also other possible explanations for negative test results in these cases. False negative tests are actually not uncommon with CIRDC. Some organisms are difficult to culture outside of the body, especially if an animal has started an antibiotic therapy. In many cases, viruses stop shedding before or shortly after symptoms even begin, making them difficult or impossible to detect on molecular tests.

We may also be seeing a statistical anomaly. Like with any disease, there is an expected range of symptoms, with the vast majority falling under a “bell curve” with extremes on both ends. In the case of CIRDC, most dogs present with the coughing/sneezing/discharge described above, but a small percentage won’t have any symptoms at all and, on the other end of the spectrum, another small percentage will become extremely sick and develop pneumonia. This has led some to speculate that, because we’re seeing more respiratory disease in general compared to the last 2 years (attributed to a decline in vaccination rates during COVID), maybe we’re simply seeing more extreme cases as a function of the overall increase in case rate?


So the jury is still out on why the disease is a mystery.

Yes. There are multiple state diagnostic labs and veterinary colleges currently investigating these recent cases, but findings have been inconclusive to date. Further complicating matters, there are widely variable reporting standards from state to state and there is no universal veterinary disease database, all of which makes it challenging to track diseases in pets at scale. We are currently recommending testing more proactively than we have historically to help build a shared database of information for veterinary infectious disease researchers.


Have we seen this disease in NC?

Well, since we can’t diagnose something that hasn’t been identified, this is difficult to answer directly. In the weeks leading up to Thanksgiving, local veterinary clinics—including Truss Vet—saw a substantial uptick in respiratory disease in general. We and local emergency care partners have also seen a handful of canine infectious respiratory cases we would certainly consider “atypical,” that is, they were more severe and occurred in healthier animals than we would generally expect to see. But it’s unclear whether they were caused by the same organism(s) responsible for what was seen in Oregon versus simply extreme examples of the usual pathogens we deal with in CIRDC cases. We’re simply urging awareness and extra diligence at this time.


How concerned should I be for my dogs?

Not very concerned; just aware. Based on what we know about how most respiratory diseases are spread, dogs that rarely leave the house are likely at low risk for infection. Further, the number of cases we have seen seems to have decreased in the last week, offering some hope that if we’re dealing with something novel it may not be as contagious as most of the CIRDC we see. At this time, dogs that begin showing signs of cough should still be considered more likely to have some flavor of traditional “kennel cough” than the reported mystery illness, so there is no reason to panic. That said, pet owners should be taking precautions to keep their pets safe, and dogs that do begin showing any respiratory signs should be evaluated by a veterinarian quickly and managed conscientiously in light of recent events.


What can I do to protect my dog(s)?

There are likely steps that can be taken to minimize your dog’s risk. Most respiratory diseases are spread by way of respiratory droplets from sharing air and proximity with other dogs, or sometimes through “fomites” (i.e. clothing, toys, or other materials that have been exposed to a sick animal). 

  • Avoid close contact with other dogs: boarding and doggie daycare is physiologically stressful for pets (even when it’s fun!) and can every-so-slightly weaken the immune system. More directly, it also represents a high-density environment where dogs share air, water bowls, toys, and enjoy close physical contact. If your dog must board, be sure to ask whether they have had any cases and what steps they are taking to mitigate risk.
  • Use caution when traveling with your dog: where you are traveling, others are traveling too, which means airports, bus/train stations, rest stops, etc are all seeing a mix of dogs from all over, some of whom could have been sick.
  • Practice good hygiene: it goes without saying, but washing your hands is still one of the best ways to prevent the spread of bacteria and viruses. Pick up your dog’s poop on walks and dispose of it in a trash can. If you work in a veterinary, pet care, dog boarding/grooming facility, or anywhere else where there are coughing dogs, consider stripping and washing your clothes immediately after returning home
  • Make sure your pet is up to date on all recommended vaccines: vaccines for respiratory disease (e.g. Bordetella, Parainfluenza, Canine Influenza Virus, etc) may offer protection, help prevent complicating co-infections, and help stimulate innate immunity that gears up the body to fight infections. 

Don’t wait if your pet is showing symptoms: Under the circumstances, it makes sense to exercise caution. If your pet is showing even mild signs of respiratory disease, consult with your veterinarian, or if she is unavailable, reach out to Truss Vet – Veterinary Urgent Care.


Is my family at risk of getting sick from my dog?

Currently, this infection is believed to be limited to dogs. Historically, respiratory diseases shared between dogs and humans are exceedingly rare.


What signs should I watch for?

Any of the following:

  • Sneezing and/or nasal discharge
  • Coughing/hacking
  • Eye discharge
  • Decreased energy level
  • Decreased appetite or disinterest in food
  • Fever (> ~103º at rest; ear thermometers work well in dogs!)
  • Increased respiratory rate and/or effort
  • Purple, blue, or otherwise discolored gums (this is an emergency and indicates poor oxygenation — do not wait!)


Other reputable organizations tracking this disease


Local health resources for your sick pet