For over the last year, upper respiratory infections have been increasing, even among vaccinated dogs. Kennel cough or Bordetella bronchoseptica (the main bacterial agent at the core of kennel cough) is one of the most common pathogens involved with canine URIs. 

Dog sneeze
Dog sneeze

This year has been busy with many veterinarians seeing multiple canine coughing and sneezing every week. The question is, why? 

The veterinary community is still not sure what’s going on. It does seem like there’s increased of URI activity over a lot of North America right now, and it’s been going on to some degree for quite a while. When we think about increases in respiratory disease reports, there are a few  potential causes, here are a few possibilities:

Increased disease caused by the same cast of characters

Coughing dog
Coughing dog
  • Kennel cough is highly contagious and other opportunistic viruses and bacteria-like organisms associate with Bordetella to cause a respiratory complex. And when testing is done, it’s usually the common mix of bacteria, bacteria-like organism and viruses

  • A few potential reasons for the increased disease from these pathogens can be postulated. One is there’s more dogs mixing with each other now as people start to increase activity and get together post-lockdown as well as more adopted dogs since COVID. People are also being more social and that means more dogs socializing with other dogs. In addition, some regions of the US due to lockdowns experienced staff shortages and some folks didn’t want to go anywhere that wasn’t considered absolutely essential – in essence, less vaccinations may have been given.  

  • Another thing to consider is that a lot of practices are using the oral Bordetella instead of the intra-nasal. Granted, most dogs do not like having liquid squired into their nostrils and oral vaccines are much easier to administer than intra-nasal vaccines. The possible problem is oral vaccines only protect against Bordetella one of the main parts of the Bordetella complex, while intranasal vaccines protect against Bordetella and canine parainfluenza virus (CPIV). That’s important because CPIV is often found in dogs with upper respiratory infections.

    As a side note, at our practice in Houston Texas where about 50% of respiratory illness are sent to the lab to identify the causative agent, the majority of other or solo organisms that have been found are mycoplasma with a much lower number of parainfluenza detected and in one case, a dog-specific corona virus. 

Increased disease caused by a new pathogen

dog receiving an intra-nasal Bordetella
vaccine with parainfluenza

Another question, is there a new pathogen involved? The veterinary community is always on the lookout for something new, but nothing is apparent yet.

With a new virus, we’d be more likely to see widespread transmission in exposed groups, since no dogs would have any immunity. We’re not really seeing that. The cases being reported are more sporadic, as we’d expect with our typical causes of the Bordetella complex.

However, we can’t rule out a new pathogen completely, and there are undoubtedly various causes of canine upper respiratory infections (mainly viral) that we simply haven’t identified yet.  

Increased reporting of disease

  • Another reason we are hearing about increased infections is probably part of the increased use of social media, so word spreads quickly. Further, it feeds on itself. When there’s more buzz about sick dogs, more people that otherwise wouldn’t have said anything chime in. So, we probably hear about a greater percentage of sick dogs simply because people are talking about them when they otherwise wouldn’t have.

  • Also, as more people are at home with their dogs, we probably hear more about the typical mild cases of Bordetella, because owners notice even small occasional coughing when the dog is beside them all day.

What about SARS-CoV-2?

  • SARS-CoV-2 is unlikely to be playing a role. We can never say never, since the COVID-19 pandemic is a dynamic situation and we don’t know much about recent variants in animals. However, what we know so far is that infection of dogs and cats with SARS-CoV-2, while possible, rarely causes clinical disease in dogs and cats.

What about canine influenza?

  • Canine flu certainly can cause large outbreaks of respiratory disease in dogs. It spreads quickly because of limited immunity in the dog population. There has been some canine flu activity in a couple places in the US in the past few months, but these seem to have burned out (or at least died down) relatively quickly.

What can people who are worried about their dogs do?

  • Reduce contact with large numbers of unknown dogs. Just like with other respiratory pathogens, the more contact, the greater the risk of encountering someone that’s infectious.

  • Reduce contact with sick dogs. This can be harder but it’s common sense: if a dog looks sick (e.g. coughing, runny nose, runny eyes), keep your dog away from it.

  • Keep sick dogs at home.

  • Avoid things like communal water bowls in parks that are shared by multiple dogs. Bring your own portable water bowl and bottled water

  • Get your dog vaccinated against kennel cough if it socializes with other dogs. 

  • Consider testing your dog with a respiratory PCR if your dog gets sick. Testing is useful to help figure out what’s going on and helps us predict the length of illness and if any specific treatments are needed maybe to help control things. That said, if your dog is bright and alert and eating and drinking well, it’s hard to rationalize the cost of this test as most cases with a little help are self limiting in 9-14 days.

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