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Canine Influenza – Symptoms, Diagnosis & Treatments of Dog Flu

↯ Key takeaway points

  • Canine Influenza is a highly contagious virus that primarily spreads through large-particle respiratory droplet transmission
  • There are two different kinds of Canine Influenza virus in North America: H3N8 CIV and H3N2 CIV
  • Prevention involves maintaining good hygiene, making sure your dog's diet is balanced, and avoiding contact with an unknown dog
  • Vaccines are available, but there may be side effects such as anaphylaxis and hypersensitivity reactions
  • Symptoms include persistent cough, loss of appetite, lethargy, fever, nasal discharge, and breathing difficulties; treatment focuses on supportive care and keeping the dog comfortable.
Breeding Business is passionate about all sorts of domesticated pets. They have written dozens of articles across the web.
Zoo and wildlife doctor in veterinary medicine passionate about animal welfare and preventive medicine.
Published on
Friday 22 February 2019
Last updated on
Tuesday 20 June 2023
dog flu
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You may notice some social media feeds warning the pet owners about a highly contagious Canine Influenza, aka dog flu, that is raging all over the USA. Even some newspapers like Fox news and Newsweek also publishing their reports about the flu.

The truth is, yes, some dogs are catching flu in different US states. To be honest, there is also several shocking news about local outbreaks of the flu. For example, a flu outbreak affected more than 1,000 dogs in Chicago in 2015.

But no, there is nothing to panic. In this article, we will cover everything you may need about the canine influenza virus and dog flu.

What is the Canine Influenza Virus?

The canine influenza virus, also known as dog flu, belongs to the type A Influenza virus genus in the family Orthomyxoviridae. It is primarily adapted to dogs and named after two surface antigens, neuraminidase (N) and hemagglutinin (H) proteins. There are 9 neuraminidase antigens (N1 to N9) and 16 hemagglutinin antigens (H1 to H16).

There are two types of canine influenza virus found in North America: H3N8 CIV and H3N2 CIV.


originated from the A/H3N8-type of equine influenza virus (EIV) in 2000 and initially infected horses before spreading to ducks and dogs. This virus shows the same growth level on different hosts but prefers α2-3- over α2-6-linked sialic acids to infect the hosts. H3N8 was first reported in racing greyhounds in the US in 2004, and an outbreak occurred between 2004 and 2005, affecting almost 20,000 dogs from 13 different states.


H3N2 CIV is a more recently encountered strain that is believed to originate from Asia. It was first reported in South Korea and was introduced to the US (in Orange County) in 2015 through an imported dog from South Korea. This virus caused a severe outbreak in many regions after the initial breakout.

In summary, the canine influenza virus primarily affects dogs and is named after two surface antigens. There are two types of the virus found in North America, H3N8 CIV and H3N2 CIV. H3N8 CIV originated from the A/H3N8-type of equine influenza virus in 2000 and was first reported in racing greyhounds in the US in 2004. H3N2 CIV is a recently encountered strain believed to originate from Asia and was introduced to the US in 2015, causing a severe outbreak.

How Does the Dog Flu Virus Spread?

This virus spreads primarily through large-particle respiratory droplet transmission. The spreading process may occur in two approaches: direct contact and indirect contact.

Direct contact includes muzzle-to-muzzle, nose-to-nose, friendly licks (dog kisses), or through the air. When an infected dog barks, sneezes, or coughs in the open air, it makes the air affected. Whenever a healthy dog sneezes on that air, it becomes infected too. An infected dog sends aerosolized particles almost 20 feet through the air!

The indirect contact may happen through physical commodities such as water bowls, feeding bowls, toys etc. This Influenza virus can live on those up to 48 hours!

Is Canine Influenza Contagious?

The Canine Influenza virus is a very contagious virus that affects dogs. In recent years, this flu has caused concern for pet owners.

According to the Centers for Disease Control and Prevention (CDC), the 2017/2018 flu season was particularly concerning. In the first week of January, there were 22.7 hospitalizations per 100,000 dogs in the US due to the flu, which was twice as many as the previous week

Watch this quick video from National Geographic to get a quick recap on what the Canine Flu is all about.

Prevention of Canine Influenza Virus

Good hygiene prevents most of the viruses. Always maintain a healthier procedure while handling your own or any unknown pet. Most importantly, the pet owners should take total responsibility for their pets as well as use their common sense to keep their dogs safe from dog flu.

To help the dog owners, we have listed a few veterinarians suggested tips to prevent this fatal virus.

➢ If a dog suffers from an active respiratory illness or if he recently recovered from any kind of respiratory illness, keep it strictly at home. A couple of weeks will be a good choice. But try to make it to 4 weeks: it’s the safest choice. The affected dog can fully recover from the illness during this time. It also prevents the affected dog from spreading potential infection transmission to other dogs.

➢ Inform your veterinarian if your puppy stayed at boarding kennel recently.

➢ If you have to send your puppy in a boarding kennel in the near future, research about that first. Make sure the kennel is safe from viruses and other infectious diseases. You know, there is nothing more important than safety.

➢ Do not allow your doggy to share dishes or toys with an unknown dog.

➢ Ensure a balanced diet for your dog. You should also feed health supplements if your veterinarian suggests doing so.

➢ Thoroughly disinfect any equipment, clothing, or surfaces that might be infected with respiratory secretions. A commercial disinfectant or 10% bleach is an ideal choice for this.

➢ Thoroughly wash your hands before AND after you are having contact with another infected dog.

➢ If your dog has been lost for a day or even for a few hours, contact a reputed dog rescue organization first and visit the veterinarian as soon as you rescue your dog and the state hospitals for an experienced veterinarian.

➢ Be aware that your pet is updated with all canine influenza vaccines.

➢ Mostly, remain alert about canine influenza outbreak in your area.

Vaccines for Dog Flu

The United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) approved the first canine influenza vaccine in June 2009, which was a significant milestone in veterinary medicine.

Currently, the most commonly used vaccine for dog flu is called the Bivalent Vaccine. This vaccine can protect against both H3N2 and H3N8 CIV strains and is recommended for healthy dogs that are at least 8 weeks old. To ensure the best protection, it is essential to administer two doses of the vaccine, three weeks apart.

However, pregnant dogs cannot be vaccinated. Additionally, some dogs may experience side effects after receiving the vaccine, such as anaphylaxis or other hypersensitivity reactions.

To summarize, the canine influenza vaccine has been approved by the US Department of Agriculture’s Animal and Plant Health Inspection Service, and the Bivalent Vaccine is the most commonly used vaccine to protect against two strains of the virus. It is crucial to follow the recommended vaccination schedule to ensure the best protection for your furry friend. While pregnant dogs cannot receive the vaccine, most healthy dogs can get vaccinated without experiencing any side effects

Symptoms of Canine Influenza Virus

Almost 80% of infected dogs show dog flu symptoms. We’ve compiled a list of symptoms to identify whether your pet is sick or not?

Persistent cough

Does your dog cough persistently after staying at a kennel? Oops! It’s perfect morbidity of having canine influenza. This soft or wet cough may last 3 to 4 weeks.

Additionally, they will sneeze continuously. The inflammation of nasal lining causes this. Do not confuse dog flu with kennel cough.

Loss of appetite

Your dog won’t express any interest in food. Even when he feels hungry, you cannot feed him. The loss of appetite is quite natural for one or two days. But if it continues, you must be worried.


Few dogs are sleepy by nature. That’s why the pet owner didn’t notice the sleep cycle of their pets. But sleepiness doesn’t mean they sleep all the time.

However, the affected dog will feel sleepy all the time. He will lose interest in playing with you like before. Rather than that he will like to doze on his tent or kennel.


Actually, fever isn’t a disease at all. It is a symptom of diseases. Like most other diseases, canine influenza infection also causes the fever to your pet.

The normal temperature of a healthy dog lies between 99.5F and 102.5F degrees. So, you should read the accurate body temperature using a thermometer. You may also feel their paws and ears manually. You will feel hot if your dog has a fever.

Nasal discharge

Along with cough and fever, liquid nasal discharge also a common sign of flu infection. The nasal discharge directly connected with the respiratory issue. As the worst case scenario, you may notice colorful discharge mostly greenish. Trust me, it’s really a bad sign.

Breathing difficulties

An increased respiratory rate and breathing difficulties cause several diseases like canine influenza H3N2 infection, pneumonia etc. If you do not take quick action, it may affect the lungs too.

There are several signs of canine influenza virus. If your dog shows any of these signs, contact your veterinarian right now.

dog flu guide
Guide to dog flu and the canine influenza viruses (H3N2).

Dog Flu Treatment

As the old saying goes, “prevention is better than cure.” So, it’s essential to take preventive measures to protect your dog from the flu rather than relying on treatment.

Unfortunately, there is no specific cure for canine influenza. However, you can support your dog and keep them comfortable during the illness. Some dogs may need extra attention and care. Follow your veterinarian’s recommendations carefully.

If your dog’s condition does not improve, consult with your vet again. They may suggest a nutritional plan or prescribe antibiotics. Keep in mind that treating a severely infected dog can be expensive. Consider getting pet insurance to help you cover the costs.

Canine influenza can affect any dog, but with proper care and attention, your pet can recover from the illness. If you have any questions about canine influenza virus, please leave a comment below. Our expert team will get back to you as soon as possible.

In conclusion, remember that prevention is the best approach to protect your furry friend from canine influenza. Stay happy and healthy with your dog!

One comment on “Canine Influenza – Symptoms, Diagnosis & Treatments of Dog Flu”

  1. Wayne

    Hi, my pet, a cocker spaniel now 8 years old, has been showing some of flu symptoms: •Sneezing •Nasal discharge, • Purulent nasal discharge •Lethargy
    it has been going on for a couple of months, initially I thought it was allergy, but then I saw quite a bit of nasal discharge. A flu has no discharge, but should have run its course in 2- weeks, correct? His appetite remains good, mostly remain energetic, no cough. Questions:
    1. Is it flu or something more serious?
    2. What are symptoms of a dog pneumonia?
    3. what should I do now?
    Thanks a million!

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