Update on Canine Respiratory Disease 2023

New states reporting and thoughts on causes

Hey everyone, after my previous post on the subject, people have been asking for updates on the canine respiratory disease cluster (I am starting to boycott the inflammatory label of “mysterious”). There is not a ton of new information, but some additional data is trickling in.

State Reporting

As of this morning, at least 15 states (up from 14) are reporting cases of this respiratory syndrome. Several cases have been reported by one vet in Nevada, but that is considered unofficial at this point. I continue to be surprised that neither New York nor Texas have apparently reported cases of this syndrome, both as high population states, and located geographically near several regions with a lot of cases (particularly New York).

(Source)

Some Veterinarians Cast Doubt that There is Anything New

I came across this NPR article late last week that interviewed several experts about their thoughts, and some of them largely downplayed the idea that there is anything new here.

Dr. Jane Sykes, a veterinary internist at UC Davis, said:

“It's entirely possible that there are just a ton of different bugs and viruses causing disease in different parts of the country," says Dr. Jane Sykes, a professor at UC Davis School of Veterinary Medicine who focuses on infectious disease. "We just have to be a bit careful about panicking.”

And Dr. J Scott Weese at the Ontario Veterinary College, also an internist and infectious disease expert (who runs the informative Worms and Germs blog) said:

“Two things keep getting mixed up: Do we have more disease? And do we have something new? Because those are not necessarily connected.” Weese says it seems that certain parts of the country are experiencing an uptick in canine respiratory illness. However, it's possible the deluge of media coverage and attention on social media has created the appearance of a nationwide outbreak that may not exist in reality. “I get an email a couple of times a week saying, ‘hey, are we seeing more respiratory disease in dogs?” he says, “But I've been getting that email for like five years.”

It is worth taking this position seriously. There is definitely a scenario where a generalized increase in the background rate of multiple infectious agents is coincidentally occurring around the same time, and the element of media hype is throwing gas on the fire. On his blog, Dr. Weese points out that the last few years have created a lot of factors that could increase the baseline rate of respiratory disease in dogs:

• More dogs

• Disrupted veterinary care (less vaccination)

• Changes in human activities (e.g. more remote work, maybe leading to fewer dogs at day care and therefore less kennel cough vaccination)

• Other changes in human activities that alter how dogs interact

• Changes in the types of canine respiratory disease vaccines we use

• Earlier pandemic restrictions reducing the normal level of exposure to kennel cough pathogens and vaccination

Reasons There May Be Something There

That said—and I am by no means an infectious disease expert—I’m skeptical of the idea that this is a total nothingburger for a few reasons. First, while we don’t have a robust national monitoring system for some of these poorly-defined disease syndromes, we do have pet insurance data on claims for various disease types. Trupanion pet insurance data from Colorado and Oregon, two of the harder hit states, show a substantial increase in respiratory claims about 6 months ago (before there was much media attention on this story), which have since subsided, as you would expect for an outbreak curve.

(Source)

(Source)

On the other hand, California’s curve does not look the same, and shows a more gradual increase over several years, which doesn’t fit the pattern in OR or CO:

(Source)

Second, as I mentioned, the time and geographic distribution of reported states strikes me as unusual if this is primarily being driven by panic and news/social media hype. You would expect the case distribution to be more randomly dispersed across the country and to follow big population centers. You’d expect a surge of cases in New York and Texas, but as I mentioned earlier, there apparently isn’t. Furthermore, why wouldn’t these fears have gone “viral” (excuse the pun) in 2020-2021 when everyone was staying at home in lockdown staring at their phones and hyper-fixated on both respiratory disease and any new symptom their pets showed?? Despite a huge surge in vet visits in 2021, respiratory disease was not notably increased to the degree it is now.

Finally, I have heard some people suggest that it shouldn’t be surprising that antibiotic resistance is increasing when we prescribe huge amounts of those drugs (particularly doxycycline) left and right. Antibiotic resistance is real, and something we should be concerned about, but that would be unlikely to have suddenly evolved in multiple places across North America in the span of a few months. That’s just not how bacterial evolution works.

Is It A Weird New Bacteria?

The short answer: we don’t know.

This Scientific American article from yesterday goes into the backstory of several labs that are investigating potential causes of this respiratory disease cluster:

In addition, the infectious agent Needle [a veterinary pathologist at the New Hampshire state diagnostic lab] and his colleagues are tracking doesn’t seem to be closely related to known pathogens, and it can’t be cultured in the lab. “If it were just like a new flavivirus [a class of virus that can cause diseases such as yellow fever and dengue in humans] or a new influenza or something like that, that would have been ‘bing, bang, boom’—it would have been [identified in] a couple weeks,” Needle says. “But since it’s weird, it took some digging.”

Their lab and some others have found DNA sequences from an atypical bacterium in some patient samples, but it is not found in all cases, and it’s too early to tell if this is the (or even a) pathogenic cause or simply an innocent bystander / incidental finding. Some sources have described this possible organism as similar to Mycoplasma or Mycoplasma-like, but other sources (like earlier reporting out of Oregon) thought the case pattern fit a viral agent better, and there is enough uncertainty that I’m withholding judgment until I see more data.

Take-Away

I summarized my view on this evolving situation to a vet friend recently:

“Don’t panic, most dogs recover & we’re studying it” = good messaging

“lol this is just kennel cough and news media freak out” = bad framing

The main action items for pet owners at this point are similar to what I’ve said previously: Don’t be too afraid, use common sense to reduce spread of respiratory disease among your pets, keep up with preventative care and vaccinations, and monitor reliable veterinary sources for any news updates.

I will continue to update you as new information becomes available. Stay tuned!