Why don't we know the name of this mysterious illness?

Originally published 30 November 2023. Retained for reference — if your dog is unwell now, please book a sick visit rather than relying on an older article.

The question on the mind of many dog owners right now is: what is this mysterious respiratory illness spreading across the country, and why don't we have an answer yet? The simple answer is that it's a complex problem. The truth is that we often do not know the exact name of respiratory infections.

If clients bring their pets in for a respiratory virus, they often wait until the pet is very sick and not getting better, and by then the picture changes. There are more infectious organisms involved and we don't know which one started it or which one is most problematic. Buckle up — this will be a long explanation, but judging from the number of questions I am answering about this right now, I think a long explanation is necessary.

As a veterinarian, I see infectious coughing dogs nearly every day. Outbreaks are not that unusual. Since coughs are spread by aerosolised respiratory droplets, they can spread rapidly, making respiratory outbreaks more common — especially in a kennel where dogs are barking, because the force of the air in a loud bark causes the droplet to travel further. But you don't have to be in a kennel to catch an infectious cough. I wish more people understood this.

It's a syndrome, not one disease

Canine Infectious Respiratory Disease Complex (CIRDC) is a syndrome of diseases caused by several different bacterial and viral pathogens that mostly affect the upper airways, like the trachea and larger airways in the lungs. We call it collectively kennel cough, but it is not limited to kennels. Kennel cough is an upper respiratory infection of the large airways and it has been around forever. Sometimes it turns into pneumonia, which is more serious. But again, this is not new.

Viruses are constantly evolving, and antibiotic resistance is a constant worry for medical professionals. Respiratory infections causing cough and pneumonia are as old as veterinary medicine itself, even if they are slightly changed. This topic is old news to veterinary professionals but new to pet owners, so I want to give you the scoop.

What is happening is most likely an outbreak

Veterinarians believe they are seeing more cases. Some are reporting their patients staying sick longer than expected with typical kennel cough, and there have been more cases of acute pneumonia. The veterinary community is asking for more sick patients to be tested so we can know if there is something new going around, or if there are just more of the known pathogens. Outbreaks are not necessarily a new thing — the public often never hears about them.

I remember a couple of novel viral outbreaks in my career, and here is what happened behind the scenes. Veterinary diagnostic laboratories, state, university, and local veterinarians worked together to identify and treat the new strain of a virus, and the public knew very little about it. We didn't even give these viruses new names, just a new number on the end. For example, the strain of Canine Influenza H3N8 was discovered in 2004; today this strain is included in the canine flu vaccine. Did you know that there are actually four strains of parvovirus? It's okay — your vet knows.

It's like Ocean's Eleven with pathogens

These infections often occur as co-infections. More than one pathogen is involved. Pathogens are opportunistic. One infection may weaken the immune system, the natural defences of the respiratory tract are overwhelmed, and another pathogen joins the party.

Think of it like a gang of criminals attacking a neighbourhood: some hack the security system (the immune system), and others climb over the fence. If we remove the ones who attack the security system, the others can't get over the fence. So sometimes antibiotics help kennel cough but they don't completely resolve the disease. The immune system does that, when given enough time.

Why testing is problematic

Who needs to be tested?

Dogs with a respiratory infection. Healthy dogs may have an organism in their throat but that doesn't mean much, so routine screening is meaningless. Before an outbreak is obvious, many dogs with an infectious cough will get better before a test is returned. Testing is usually reserved for cases that seem unusual.

What to test for?

There are at least 11 known canine respiratory pathogens, which means the respiratory panel is a little pricey and has to be timed perfectly. These are the most common organisms to cause outbreaks in groups of dogs:

• Canine distemper — causes severe disease, but most of our pets are vaccinated against this with the distemper/parvo combo vaccine, and it is therefore less common.
• Pneumovirus — capable of causing large outbreaks among dogs in close proximity, like shelters, but usually self-limiting.
• Influenza — there are multiple strains, and we know the strain H3N2 was active in South Carolina and Georgia.
• Streptococcus zooepidemicus — this bacteria can cause severe and sometimes fatal pneumonia, and might cause dogs to cough up blood.

When to test?

We have to test patients in the first three days of infection for the test to be accurate. This means timing is likely the biggest barrier to effective testing. We have to get the organism on a swab — and the organism moves. Infections start in the nose, go to the throat, then travel down to the lungs. We can swab the nose or throat, but we can't swab the lungs. Because infections start with subtle clinical signs like lethargy or inappetence, the window of opportunity is fleeting. A test on day 7 that is negative for 10 organisms doesn't mean the infection is mysterious — it might just mean we didn't test in time.

Where to collect the sample?

Technique is critical. If a vet has an opportunity to test a dog early in the infection, you have to swab its nose. Did you ever have a COVID test done at the doctor? It felt like they swabbed your brain, right? Have you ever tried to stick something up your dog's nose? I give the activity zero stars — they hate it as much as we do, but vets get it done.

In order to solve the mystery illness, we need to test correctly. That means testing the right dog at the right time with the right test using the right technique. Easier said than done.

An ounce of prevention

Here is the most important thing I learned in my infectious disease class: your pet's immune system kills most of what attacks them before they can even get sick. And we can boost their immune system by vaccinating them.

Why vaccinate when we don't know what this infection might be? Remember the part about co-infections. Respiratory tract infections are a big party for the bad guys. Don't miss a chance to protect your pet's security system.

• DHPPV / distemper vaccine — distemper is included in the 5-in-1 vaccine with adenovirus, parainfluenza (types 1 and 2) and parvovirus. Given several times to puppies, then every 1 to 3 years.
• Kennel cough vaccine — includes Bordetella bronchiseptica, adenovirus-2 and parainfluenza. We vaccinate annually, but with high-risk dogs, every six months is best. People might believe this vaccine is only necessary for dogs that board or visit dog parks, but remember: respiratory diseases spread not only dog to dog, but from human hands to other dogs. And who can resist petting a dog?
• Flu vaccine — usually recommended for dogs who are high risk and visit a groomer or boarding facility often.

Reducing your dog's risk

There are high-risk situations wherever dogs gather nose to nose: training classes, dog parks, shelters, boarding facilities, grooming salons, and even crowded veterinary waiting rooms.

For dog parks, grooming salons, and boarding facilities, only choose facilities with a vaccine policy. If you can use a pet sitter in your home, that is best. Unnecessary play dates are not advised. When you must take your dog around another dog, check that both dogs are healthy, vaccinated, and have not recently been in a high-risk environment. If your dog is slightly lethargic or skipped a meal, stay home — or call your vet.

Remember that dogs don't have to seem sick to spread disease. Wait a few days after taking your dog to a dog park before allowing them around other dogs, especially high-risk individuals.

Some dogs are high-risk individuals

Every respiratory infection is not the same for every pet. French Bulldogs, English Bulldogs and Pugs are brachycephalic breeds — they have short noses, narrowed nostrils, and long soft palates. They have a harder time clearing a respiratory infection and often get pneumonia. Elderly and immunosuppressed animals, such as dogs with Cushing's disease or diabetes, are also high risk. If you own a high-risk dog, be extra diligent.

During an outbreak, I assume all of my canine patients are at higher risk and recommend caution and vaccination. We have no reason to believe any other species is involved — this is a dog-only concern.

How we treat these dogs

We are not helpless. For viruses, supportive care plays a big role; antivirals are not as useful as antibiotics overall. Mostly, canine respiratory infections are treated just like we treat a cold for ourselves. I can hear my Mom telling me: stay hydrated, eat something warm and soothing. That is sound advice. I will also add: take the antibiotics.

For bacterial infections, antibiotics are important. We don't just grab the strongest antibiotic on the shelf, because we don't want to cause antibiotic resistance. If the first line isn't working, or if our patient is suddenly extremely sick, then we might choose a stronger drug.

We've got this

Veterinarians are talking to each other, urging caution, but not panicking. We treat pneumonia and upper respiratory infections every single day, and we use more than just antibiotics — nebulisation, IV fluids, Cerenia, coupage, oxygen, bronchodilators, or steroids.

As for solving the mystery, realistically we may never solve it. It might just go away. Respiratory outbreaks often slow down on their own, sometimes before we have enough data to name them.

To summarise

• Don't take unnecessary risks
• Vaccinate your dogs
• Get medical attention earlier rather than later
• Submit to testing if your vet recommends it
• Give the antibiotics as directed if prescribed

Related reading: Respiratory Alert and Dr. Jones on the illness reaching Jacksonville. Bordetella and influenza vaccinations are available as part of our mobile visits.