How To Tell the Difference Between Dog Flu and Kennel Cough?

When we humans get a cough or cold, we often wave it off without much thought, but if our beloved pup so much as gives a single sniffle, we panic. Worrying as a pet parent is natural and, of course, we should always keep an eye out for anything that seems wrong with our pet’s health – but having the right information can make the difference between freaking out and understanding.

Coughing in dogs can be caused by a variety of conditions, but internet searches for “why is my dog coughing?” will most likely bring up kennel cough and dog flu. This can be quite confusing because in the UK what is sometimes called ‘dog flu’ is actually kennel cough. This is because true canine influenza virus is luckily not prevalent in the UK. This means we end up using the terms interchangeably. These two conditions both affect the respiratory system but stem from different causes.

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Still with us? Just about? Good. Ahead, we explain the differences between these two cough-producing conditions and outline everything pet parents need to know. We’ll look into symptoms to look out for and explain what to do if your pup starts coming down with a cough. Knowing these differences will help you seek the most appropriate care at the right time, and give you confidence that you’re supporting your pup in the best way.

Understanding the terminology

Kennel cough, dog flu, canine influenza… how‘s a pet parent meant to know what‘s what?

What is kennel cough (CIRDC)?

Kennel cough is also known as canine infectious respiratory disease complex (CIRDC). It is an endemic disease, which means it’s always present in the UK dog population, waxing and waning through seasons and locations. 

CIRDC has various common bacterial and viral causes, and all of them come under the umbrella term of kennel cough. The most common causes are a bacteria called Bordetella bronchiseptica and viruses such as canine parainfluenza (not to be confused with influenza).

What is true canine influenza virus?

True canine influenza is a highly contagious respiratory infection caused by specific influenza viruses, H3N8 and H3N2. While found in other places around the globe and endemic in Asia and North America, it is not prevalent in the UK. 

• H3N8 variant: first discovered with an outbreak of respiratory illnesses at a Greyhound track in Florida, USA in 2004. This was caused by a mutation in an equine influenza virus.

• H3N2 variant: first discovered in 2007 in South Korea, having originated in birds. It was then detected in the US in 2015.

There has been no evidence of the spread of canine influenza viruses to people, and it is different to the seasonal flu humans can get.

Why the confusion?

It is very easy to get confused by these similar names and symptoms, particularly when kennel cough doesn’t have one specific cause, and isn’t only spread in kennels. The term canine infectious respiratory disease complex is more correct to help make sense of this, but kennel cough is less of a mouthful to say and so the term has stuck around.

Key differences: kennel cough vs canine influenza 

Kennel cough symptoms (common in the UK)

Kennel cough symptoms are usually mild and self-limiting. They usually pass within 7–14 days but the cough can linger for longer and be the last symptom to resolve.

Primary symptoms

While kennel cough can be from various causes, the main symptoms are primarily upper respiratory-related, such as:

• dry, hacking cough

• sometimes ending in a ‘yak’ sound or bring up frothy phlegm

• otherwise bright and well within themselves

• cough can be brought on from barking or excitement or pulling on their lead

• mild nasal discharge

Additional symptoms

While less common, these symptoms can also occur with kennel cough:

• voice changes when barking

• increased nasal discharge

• lethargy

• retching

 What’s usually absent

• marked lethargy

• loss of appetite

• difficulty breathing

• generalised illness

• severe nasal discharge

• vomiting or diarrhoea

• fever

Canine influenza symptoms (rare in the UK)

Primary symptoms

As with other influenza diseases symptoms of canine influenza tend to be more widespread and flu-like, rather than just limited to the upper respiratory tract. Common signs include:

• a persistent cough

• cough often softer or more productive than classic kennel cough

• lethargy and reduced appetite

• high temperature

• nasal discharge which can become thick

• reduced appetite

Secondary symptoms

Secondary bacterial infections can occur due to the weakened immune system. With these additional symptoms may appear, these signs suggest the illness is affecting the lower airways or the whole body rather than just the throat and nose:

• worsening cough – can sound wetter or deeper

• rapid, shallow or laboured breathing

• marked lethargy 

• weakness

• refusal to eat

• thick, yellow or green discharge

• high and persistent fever

• symptoms of pneumonia

  • increased breathing effort

  • chest discomfort and increased sounds

  • collapse in severe cases

Progression

Canine influenza often starts as mild respiratory signs, such as coughing and nasal discharge but in some dogs can progress over several days to affect the lungs and the rest of the body. As the virus causes damage to the lungs, dogs can start to become lethargic and develop a high temperature. With this weakened immune system they can be prone to secondary infections, including pneumonia. Early rest and monitoring are important as prompt veterinary care can reduce the risk of complications and support them through recovery.

Warning signs requiring immediate vet attention

Even though with both conditions pups usually recover without complications and without medical treatment, it is important to monitor for signs your dog needs additional support. Look for:

• marked lethargy

• rapid, laboured or noisy breathing

• thick yellow or green nasal discharge

• loss of appetite for more than 24 hours

• a cough that worsens, becoming deeper and wetter or does not start to improve

• if your pup is very young, elderly or has underlying health issues and starts showing respiratory issues

How these conditions spread

Both kennel cough and canine influenza are highly contagious respiratory illnesses that can spread easily wherever dogs mix.

Transmission methods

Both conditions spread in similar ways:

• Respiratory droplets that are released when an infected dog coughs, sneezes, barks and even pants.

• Direct dog-to-dog contact such as nose greeting or shared playtime.

• Contaminated surfaces (fomites). This includes food and water bowls, toys, bedding, leads, collars and even us!

Humans can accidentally spread the infection through petting an infected dog, then an uninfected one. So this means it is important to always wash your hands between dogs, or refrain from petting other dogs if yours is infected.

Importantly, dogs can spread the infection before any obvious symptoms develop. Some may even continue to shed organisms for days or even weeks after symptoms have resolved. This makes it easy for infections to spread under the radar, particularly in busy environments.

As kennel cough can be caused by one or a combination of viruses and bacteria, multiple pathogens may be spreading at the same time. Canine influenza is caused by a specific influenza so can spread through groups of dogs who have little existing immunity, much like how human flu spreads.

High-risk environments for UK dogs

Certain settings can increase the risk of exposure due to close proximity, shared air space and equipment. This includes areas such as:

• boarding kennels (where kennel cough got it’s name)

• doggy daycare

• training classes and puppy groups (think first term at school sharing germs)

• dog shows

• grooming salons

• dog parks or popular walking paths

• rescue centres

• multi-dog households

Contagious periods

Kennel cough

Kennel cough has a variable incubation period depending on the pathogens involved, and can be as short as a few days to a couple of weeks after exposure. Dogs can be contagious before the cough develops as well as being able to spread infection for up to 2–3 weeks after symptoms begin. If Bordetella bronchiseptica is involved, this can be longer.

During this time your pup should not be mingling with others, even if they seem bright and well to limit the spread. As a general rule dogs with kennel cough should be isolated from other dogs for at least 7–10 days after their cough has stopped.

Canine influenza

Canine influenza typically has an incubation of around 2–4 days. Dogs can be contagious very early sometimes before obvious symptoms emerge. They may also continue to shed the virus for up to 10 days or more after infection.

Because of this lengthy infectious period dog flu spreads quickly through groups of dogs, so it is important to isolate infected dogs to limit the spread. It is recommended to isolate your pup from other dogs and dog shared spaces for a minimum of 14 days. 

Although true canine influenza is not known to be circulating in the UK, precautions such as strict hygiene are essential, as other dog viruses can spread on hands, clothing, bowls, leads and surfaces.

Prevention measures

The best way to reduce risk of infection of both kennel cough (most relevant to us in the UK) and canine influenza is through a combination of vaccination, good hygiene and sensible precautions.

Vaccinating against kennel cough is not a part of the core vaccinations your pup gets yearly, however it is an optional extra. It is recommended for your pup to get it as it can reduce the risk of infection, but also can reduce symptoms if they do become infected.

Canine influenza vaccinations are not typically offered in the UK due it not being prevalent, however it is available if requested at certain practices. This is recommended if your pup has travel plans to endemic places.

How vets diagnose kennel cough or canine influenza

As kennel cough and canine influenza can look pretty similar, especially at early stages, a structured clinical assessment is essential rather than relying on a single test. In the UK, most coughing dogs are diagnosed with kennel cough (canine infectious respiratory complex), while true canine influenza is very rare.

Your vet will go through a series of questions to gather information about your pet to try to narrow down possible causes. To build a full picture this can include:

• Your dog’s recent history and travels.

• Speed of onset and how the symptoms have progressed.

• Checking how your pup feels in themselves or any changes in behaviour.

• Physical assessment, including listening to chest sounds and checking temperature.

Kennel cough diagnosis

Kennel cough is usually diagnosed on symptoms and history rather than a test. Some of the tick boxes to diagnose kennel cough include:

• A recent history of mingling with other dogs or visiting higher-risk environments.

• A dry, harsh or honking cough

  • Often triggered by barking, excitement or pulling on the lead.

• Otherwise bright, alert and eating OK.

• Normal or slightly elevated temperature.

• No signs of systemic illness or breathing difficulty.

Canine influenza diagnosis (if suspected)

If canine influenza was suspected, which is rare in the UK, diagnosis would be more cautious and may involve:

• A recent history of travel, importations or exposure from dogs outside the UK.

• More severe or flu-like clinical signs

  • fever

  • lethargy

  • reduced or absent appetite.

• PCR testing by using a nasal or throat swab as part of a respiratory disease panel.

• Consideration of any local outbreaks or unusually severe disease in multiple dogs.

As canine influenza is not known to be circulating in the UK, testing is usually reserved for any dogs with atypical or more severe cases.

When vets order additional tests

In straightforward, typical cases of kennel cough (and canine influenza elsewhere), further testing is often unnecessary. But some signs your pup needs further investigation include:

• Having a fever, lethargy or difficulty breathing.

• If their cough is worsening or not improving over the expected timeline.

• Any concerns over pneumonia or secondary bacterial infection.

• If your dog is very young, elderly or immunocompromised. 

Additional tests can include diagnostic imaging such as an X-ray, blood tests or PCR respiratory panels to guide treatment and fully assess your pup.

Treatment

The main aspect of treatment for both kennel cough and canine influenza focuses on supportive care. It is important to monitor for complications and reducing spread to other dogs. Most dogs recover well with appropriate rest and management, but the level of treatment depends on the severity of illness, age and underlying health of the patient.

Kennel cough treatment

Most cases of kennel cough are mild and self-limiting, this means they improve without any intensive treatment.

Mild cases (the majority)

• Rest and reduced exercise: use a harness rather than collar as pulling on the lead can trigger a coughing episode.

• Good hydration and feed: try to keep appetite up with bland but yummy food, such as normal kibble with added hot water to warm with a small amount of boiled chicken (if no intolerances and it sits well with them).

• Monitoring at home: look for any changes in appetite, energy and breathing.

• Isolation from other dogs: preventing spread by keeping separate until coughing has resolved.

Additional TLC

• Add a drop of honey to meals to help soothe a sore throat from that coughing.

• Exposure to steam in bathroom after hot showers to help soothe airways.

• Using ASBRIP oral solution, for use for kennel cough, laryngitis and other respiratory issues.

Vet treatment when needed

Some dogs may need additional support depending on their symptoms. Puppies, elderly dogs and those with pre-existing conditions may also need to be monitored more closely.

Canine influenza treatment

If canine influenza were suspected, treatment would generally be similar but a little more cautious as dogs are more likely to feel systemically unwell.

Mild cases

• Strict rest and isolations from other dogs.

• Supportive care including fluids if needed and maintaining nutrition.

• Careful monitoring for fever, lethargy or any breathing changes.

• Follow up veterinary care and checks if symptoms persist or worsen.

Moderate to severe cases

Any dogs showing breathing difficulties, persistent fever or marked lethargy may require:

• hospitalisation

• oxygen therapy

• IV fluids

• chest imaging (X-ray) if pneumonia is suspected

• targeted treatment

Specific medications

• Antibiotics: if there is a secondary bacterial infection or pneumonia is suspected (does not work for the virus itself).

• Anti-inflammatory medication: to reduce high temperature and airway inflammation where appropriate.

• Cough suppressants: may help in some cases if coughing is distressing or exhausting.

• Nebulisation or airway humidification: to help loosen secretions.

Management focuses on supportive care and treating any complications that arise. With prompt veterinary treatment most dogs recover well, but recovery can take several weeks in more severe cases.

Prevention: keeping your dog safe

While vaccination and hygiene reduces risk, prevention also relies on sensible choices over your dogs routine. Avoid mixing with other dogs when a cough is circulating locally and keeping unwell dogs at home.

Small steps such as avoiding shared bowls and cleaning equipment such as collars and leads and harnesses along with reducing contact during outbreaks can significantly limit the spread of respiratory infections.

When to see a vet

Contact your vet if your dog’s cough worsens, lasts more than 7 days, or is accompanied by lethargy, loss of appetite, fever or any breathing difficulty or changes. Puppies, older dogs and those with underlying conditions should be checked over, even if symptoms are mild.

The bottom line: what UK pet parents need to know about kennel cough and dog flu

In the UK, most coughing dogs are affected by kennel cough rather than canine influenza. While symptoms can sound worrying, the majority of dogs recover well with rest and supportive care at home. It’s important to keep coughing dogs away from others and to seek vet advice if the symptoms worsen at any point or last longer than 7-10 days. With sensible precautions and vet advice when needed, most dogs make a full and uncomplicated recovery. 

Frequently asked questions

Can humans catch kennel cough or dog flu from their dog?

No. Kennel cough and canine influenza are dog specific and not considered contagious to humans. People can spread germs via their clothing or hands to other dogs, but they do not become infected themselves.

Can cats catch kennel cough or dog flu?

Cats do not catch kennel cough, and canine influenza is not known to circulate in cats. Transmission from dogs to cats is considered extremely unlikely.

My dog had the kennel cough vaccine but still got sick. Why?

The kennel cough vaccination helps reduce severity and spread, but it does not always stop dogs becoming infected. This is because kennel cough involves multiple viruses and bacteria, vaccinated dogs can still develop milder symptoms.

How long should I keep my dog away from other dogs?

Dogs should be kept separate for at least 7-10 days after the cough has fully stopped, unless your vet advises longer.

Is kennel cough worse in winter?

It can be more common in winter due to the increase in indoor mixing, reduced ventilation and seasonal viruses. But kennel cough can occur at any time of year.

Can my dog go to the groomer with kennel cough?

No, dogs with kennel cough should not go to the groomers until fully recovered. Grooming salons are a high risk environment for spreading the infection.

Should I give my dog cough medicine from the pharmacy?

No. Human cough medication should never be given to dogs, as some ingredients can be harmful and toxic.

What’s the difference between kennel cough and reverse sneezing?

Kennel cough is a persistent cough linked to infection, whereas reverse sneezing is a symptoms of brief, noisy inhalation episodes. These are often triggered by nasal irritation or allergies and usually cause no issue.

Are certain breeds more prone to respiratory infections?

Yes, brachycephalic (flat-faced) breeds are more prone to respiratory issues and are more vulnerable to complications.

My dog’s cough is getting worse at night. Is this normal?

Yes, coughing can be more noticeable at night due to the cooler air, laying flat and reduced distractions. However, any worsening overall of the cough should be monitored carefully and discussed with your vet.

References

• “Canine Infectious Respiratory Disease Complex (CIRDC).” Vin.com, 2026. Accessed 7 Feb. 2026.

• “Canine Infectious Respiratory Disease Complex and Bordetella Bronchiseptica - Small Animal Veterinary Surveillance Network (SAVSNET) - University of Liverpool.” Liverpool.ac.uk, 2019. Accessed 7 Feb. 2026.

• CDC. “About Dog Flu.” Influenza in Animals, 2024.

• “Managing Canine Infectious Respiratory Disease Complex.” Vettimes.com, 2021. Accessed 7 Feb. 2026.

• “Relevance of Novel Small Animal Viruses in UK Veterinary Practice.” Vettimes.com, 2017. Accessed 7 Feb. 2026.

• Small Animal Expert Group Annual Summary 2023 Overview. 2023. Accessed 7 Feb. 2026.

• Wasik, Brian R., et al. “THE EVOLUTION and EPIDEMIOLOGY of H3N2 CANINE INFLUENZA VIRUS after 20 YEARS in DOGS.” Epidemiology and Infection, Cambridge University Press, Mar. 2025, pp. 1–38. Accessed 12 Sept. 2025.