We’ve come a long way in terms of medical diagnostic technology in recent years. It’s now cheap and easy to identify a wide range of viruses and bacteria, including some we’ve never seen before. However, our ability to find pathogens has outpaced our ability to understand the role they may (or may not) play in disease. So, we end up in lots of situations where someone finds a “new” pathogen and we have to figure out if it’s really new (vs we just didn’t know it was there before) and whether it’s relevant.

If we test a bunch of dogs with respiratory disease, we’ll find a variety of viruses.

• Some are viruses we know cause disease, but we can often still find them in some healthy dogs too.
• Some are viruses that we suspect have the potential to cause disease, but we don’t know how relevant they are, or under what specific circumstances they may be relevant.
• Some are viruses about which we simple have no clue.

That’s a long winded introduction to a story about an outbreak of canine pneumovirus in an animal shelter in Florida.

As with any situation like this, they could be dealing with:

• A pneumovirus outbreak.
• An outbreak caused primarily by some other pathogen, but pneumovirus is co-infecting dogs and making it worse.
• An outbreak caused by some other pathogen, and pneumovirus just happened to be present in the dogs at the same time but isn’t actually part of the problem.

Details are limited in the available news articles, but it sounds like a lot of dogs tested positive for pneumovirus. Knowing how many dogs were tested, and for what other things they were tested would be helpful.  Presumably they didn’t find any of our usual suspects like canine parainfluenza virus, Bordetella bronchiseptica, canine influenza or canine respiratory coronavirus, otherwise those would have been mentioned first.

What is canine pneumovirus?

I always talk about pneumovirus when I list potential causes of infectious respiratory disease in dogs, but usually with the disclaimer “I don’t really know how important it is.” Studies that have looked at different dog populations have reported finding canine pneumovirus in 1-15%% of dogs with respiratory disease, but most often in less than 5%. Rates of 0-6.1% have been reported for healthy dogs. Finding the virus in healthy dogs doesn’t mean it can’t cause disease, it just makes it harder to determine if it’s relevant in sick dogs.

Studies looking at antibodies against the penumovirus in dogs (an indication of previous infection) have found high rates in healthy dogs, often over 50%. Dogs often develop antibodies to the virus after being admitted to a shelter. This suggests that this virus is circulating widely in the dog population and probably not causing much disease, or at least not much serious disease. When dogs mix in congregate settings like shelters, the risk of infection goes up.

My guess is that this virus does cause some disease, but likely usually just mild upper respiratory tract infections, with exposure being common when younger dogs start mixing. Once they’ve been infected, dogs are probably low risk for getting sick later in life. Shelters are high risk for exposure because of the number and variety of dogs in close quarters.  Dogs that haven’t been previously infected would be susceptible, and that could lead to an outbreak with what I’d expect to be relatively mild disease.

So, back to this canine pneumovirus outbreak in Florida.

Is it really a pneumovirus outbreak?

• Quite possibly. Shelters are high risk and if they have tested enough samples to find a lot of pneumovirus and no other causes, it’s a reasonable (albeit always presumptive) diagnosis.

What does it mean?

• Not a lot in the big picture. Outbreaks are always a pain for any shelter, and they’re taking measures to contain it; however, I wouldn’t be worried about broader community issues.  Pneumovirus already circulates and is widespread in the dog population. It’s not like canine influenza, where we’d be worried about it spreading rapidly in a largely naïve dog population. Good ol’ infection control is the key to letting the outbreak burn itself out and limiting spread outside the shelter. Nothing major required, just good use of routine practices and awareness.

Can canine pneumovirus infect people?

Not that we know, and I don’t have any real concerns about that. It’s related to human respiratory syncytial virus, an important cause of disease in kids, but there’s no suggestion that this virus infects anything but dogs.