Canine Influenza: A Comprehensive Guide

Unfortunately, dogs can get the flu just like their human counterparts. Canine influenza was first recognized in dogs in 2004. This health problem was originally thought to be related to the horse flu virus that was circulating, but when tested, genetic differences were found and it was officially declared as canine influenza.

Whatever the species, the flu virus is nasty and can knock even the healthiest of hosts down. Dog flu is no different, even the strongest of dogs can fall ill if exposed to the virus, with weaker dogs being even more susceptible.

It’s important that you know what you’re dealing with as a pet owner and how best to protect and care for your dog if there is an outbreak in your area. Armed with knowledge, you can be proactive about keeping your pet safe and healthy. Continue reading for a comprehensive guide on canine influenza (often called “dog flu”) and the ways you can help protect your dog from becoming ill.

What is Canine Influenza?

Currently, there are two strains of canine flu that are making its rounds through the United States, H3N8 and H3N2, both of which are Type A influenza virus. The flu virus is highly adaptable and changes from year to year. It’s able to infect humans as well as animals, with different strains infecting different species. The two strains of canine flu virus can actually be traced back to strains that have infected other species in the U.S.

Unfortunately, the flu virus is highly contagious, and the same holds true for canine influenza. Dogs that are exposed to other dogs with the virus can catch the flu too, and even dogs that are exposed to people who have been around other dogs with influenza can end up ill as well.

Both strains of the virus are contagious although the H3N2 strain is thought to be contagious for a longer period of time. To be safe, dogs should be quarantined and kept away from other dogs for at least 21 days after infection is detected so that they don’t pass the virus to another animal. Canine influenza is largely a respiratory disease and can present as a canine bacterial infection similar in nature to kennel cough in dogs.

What are the Symptoms of Canine Influenza?

Canine influenza can present with both mild or severe symptoms. Dogs that have a mild infection may have a moist sounding cough (although sometimes it’s dry) along with nasal secretions, or they may have no symptoms at all. Dogs that have no symptoms are considered asymptomatic, but they can still infect other dogs and should be quarantined away from other pets in the household just the same as a dog with symptoms to prevent the infection from spreading.

The cough in dogs associated with canine influenza can easily be confused with kennel cough, but the difference between the two is that the dog flu will linger. Canine flu can plague a dog anywhere from two to three weeks or longer, or roughly 10 to 30 days. Dogs that are more severely infected with the flu virus may develop a very high fever and possibly even contract pneumonia. Dogs that are severely ill can also contract secondary infections and may cough up blood and/or struggle to breathe. Bacterial pneumonia is quite common as a secondary infection and can make a dog’s recovery all the more difficult.

Other signs and symptoms of canine influenza can include:

How Canine Influenza Spreads

Any dog can be vulnerable to the dog flu virus. Those most at risk are dogs both young and old, dogs with immune systems that are already compromised, as well as dogs that are in places like shelters and kennels or that frequent places where dogs tend to congregate, such as local dog parks.

Dogs that cough and sneeze can spread the virus through droplets from their lungs, contaminating surfaces, toys, clothing, leashes, food, and water bowls, plus other objects.

Diagnosing Canine Influenza

If you know there have been recent instances of canine flu in your area and suspect your dog may have become infected, it’s important to see your vet right away.

Even if you don’t know of any other outbreaks in your area, but you suspect your dog is ill, call your vet. Most vets will start by taking a complete history and doing a thorough physical exam, including blood and urine testing.

Diagnosing a case of dog flu can be tough, and most vets will treat for flu based on their symptoms, even if they don’t have concrete confirmation of the flu virus. A serological blood test can be performed that may be helpful in diagnosis, and there are other lab tests that may be recommended as well. Sometimes vets will order X-ray’s to check for pneumonia and the severity of infection in the lungs. In some cases, they may try to get samples of cells and bacteria by giving your dog a bronchial wash.

Treating Canine Influenza

It’s important to begin treatment as soon as possible if your vet suspects your dog is ill with the dog flu, because proper care and treatment may help reduce their symptoms and prevent the spread of further infection to other dogs. In severe cases, canine influenza can be deadly and should always be taken seriously.

Unfortunately, your dog can’t be “cured” of canine influenza, the virus simply has to run its course. However, treatments can be given to help support your dog during their illness, so that they have the best chance of a speedy and full recovery.

Supportive measures for the canine flu include cough suppressants to treat their cough, and anti-inflammatories to help with the fever. If your dog has any kind of secondary infection, your vet may put them on a round of antibiotics to help clear it up.

In severe cases, a dog may need to be hospitalized and be given IV fluids to keep them hydrated and stable. And of course, your dog will need plenty of rest. Isolation is necessary as well, to prevent the spread of the disease, and you will most likely need to clean and disinfect your home and areas where your dog has been before they fell ill, so there is no spread of the virus or chance of reinfection.

Ask your vet for best practices and things you can do at home, especially if you have other animals in the house. Once your dog is back home, they will have to continue to remain isolated until their symptoms are gone, if only to be on the safe side. Dogs are usually most contagious during the incubation period of the virus, which lasts two to four days. During this period, your dog might have no other symptoms other than a runny nose. However, extreme caution should be taken since the virus is so highly contagious. Keep your dog away from other animals for at least the full, recommended 21 days.

Preventing Canine Influenza

Like the human flu virus, there are vaccines for canine influenza as well. Since there are two strains of the virus, there are two vaccines for each kind. Once a dog receives the vaccines, they will need a booster shot in two to four weeks. From there, it is recommended that the dog is re-vaccinated every year. You may also want to vaccinate your pet from other infections as well, like kennel cough.

Even though canine influenza isn’t contagious for humans, the virus can be passed along from humans to other dogs. So, if you’ve come into contact with a dog you suspect has the virus, you should make sure to thoroughly wash your hands and clothing before you are around other dogs. Regularly wash your dog’s bedding, toys, and food and water bowls to be extra cautious. You never know when and where your dog can pick up a bug, including the flu virus, and end up contaminating the house.

If your dog has the virus, again, isolation is key. Keep your dog away from other animals and try to limit your contact as well. You shouldn’t allow other species of pets around your dog either, if only because they can accidentally pass the virus along through contact, even if they can’t actually contract the illness themselves.

Additionally, if you know the canine flu is going around, try to keep your dog away from other dogs and places other animals frequent until the outbreak passes, and the virus has been contained and expunged in your local area. If you must go somewhere that other dogs are present, don’t be afraid to ask the staff if there have been any dogs sick with the flu recently, and ask what they have done or are doing to help prevent the spread of the illness.

If you are around other dogs often, make frequent hand-washing a habit. You can easily pick up the dog flu virus from somewhere else by simply petting other dogs, and then passing the bug along to your own canine pal. Washing your hands frequently can help you mitigate those risks.

Not So Fun Facts About Dog Flu

  • There are only two strains of the virus in the U.S., but a new strain has been found in China since June of 2018. It is possible this new strain may be able to move from dogs to cats, but more studies are have to be conducted for this conclusion.
  • The H3N2 strain of canine flu actually originated in birds and was then transferred to dogs.
  • Vaccines are available for both strains found in the U.S. and may be a good idea for your dog if you or they are around other dogs frequently. Talk to your vet and see what they recommend.
  • Dog flu isn’t contagious for people. Your dog can’t get you sick.
  • Rarely is canine influenza fatal. Only about 10% of dogs that have been infected with canine flu are reported to have died.
  • There isn’t a cure or a medicine for canine influenza. Treatment consists of managing the symptoms and medications are only used to treat secondary infections and symptoms of the virus like cough and fever.
  • Remember that not all dogs will show symptoms when infected. They can show zero symptoms, yet still carry the virus and infect other dogs and animals.
  • Canine influenza isn’t “seasonal” it can happen at any time of the year. If you suspect or know there’s been an outbreak in your area, take precaution to protect your dog.
  • It is possible for the H3N2 strain of canine influenza to be passed along to cats, and then transmitted from cat to cat.

Always keep in mind that even though there are currently no cases of canine influenza being passed on to humans, the flu virus is an ever-evolving beast. Just because it hasn’t yet been passed on to humans, doesn’t mean it can’t or won’t in the future.

Always take precautions when you are around dogs that are sick, both for the sake of other dogs you come into contact with as well as for yourself and your own health.


“Canine Influenza: Pet Owners’ Guide.”, Accessed 10 Oct. 2018.

“Key Facts about Canine Influenza (Dog Flu) | Seasonal Influenza (Flu) | CDC.” Centers for Disease Control and Prevention, Accessed 10 Oct. 2018.

“Dog Flu.” PetMD, Accessed 10 Oct. 2018.

“Canine Influenza Virus.” College of Veterinary Medicine – Cornell University, Accessed 10 Oct. 2018.


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