Though quite rare, canine flu can be a significant issue. Learning more about it can help you protect your dog from this highly contagious disease.

Humans aren’t the only species who suffer from the flu. Dogs can get it too, although the virus strains are different from those that infect us. While human flu is pretty common, canine flu is actually quite rare. Still, as a dedicated dog parent, it’s a good idea to have a working knowledge of canine flu, especially since many conventional veterinarians may try to pressure you into having your dog vaccinated against it (even if he’s at low risk – see below). Let’s look at what dog flu actually is, how it’s diagnosed and treated – and how you can help prevent it from affecting your own dog.

What is Canine Flu?

Canine influenza is a highly contagious viral infection affecting dogs (and very rarely, cats – these few cats were likely exposed to infected dogs). Currently, two strains of canine influenza virus have been identified in the US — H3N8, and H3N2. However, influenza viruses are able to quickly mutate and give rise to new strains that can infect the same or even different species. Both H3N8 and H3N2 can be traced to strains known to infect species other than dogs. At some point, these viruses acquired the ability to infect canines and to be transmitted from dog to dog.

Canine H3N8 influenza was first identified in 2004 and was found in racing greyhounds in Florida. This strain is believed to have developed from an equine H3N8 influenza strain that jumped from horses to dogs. Canine H3N2 influenza was first identified in March of 2015, following an outbreak of canine respiratory illness in Chicago. Prior to this, reports of canine H3N2 influenza virus were restricted to South Korea, China, and Thailand, and likely arose via the direct transfer of avian influenza to dogs. There is no evidence that either strain of canine influenza (H3N8 or H3N2) can infect humans.

Clinical Signs of Dog Flu

Like other mammalian influenza viruses, canine flu causes an acute respiratory infection in dogs. There is no “season” for canine influenza, and infections can occur at any time of the year. Clinical signs typically appear one to five days after exposure to the virus.

Dogs can have mild or severe cases of canine flu. It often resembles canine infectious tracheobronchitis (“kennel cough”). In fact, milder cases of canine flu resemble kennel cough that may last for several weeks.

Dogs that are more severely affected will be lethargic, have a fever, and show respiratory signs such as sneezing, discharge from the eyes or nose, and of course coughing. Some dogs exhibit clinical signs of pneumonia, such as a high-grade fever (104°F to 106°F) and increased respiratory rate and effort. Thoracic radiography (chest x-rays) may reveal the consolidation of lung lobes.

Canine influenza is transmitted through droplets/aerosols containing respiratory secretions from coughing, barking, and sneezing. Dogs in close contact with infected canines at kennels, shelters, and grooming or daycare facilities are at increased risk of infection. Canine influenza can also be spread indirectly via objects (food and water bowls, etc.) or people who have been around infected dogs. It is important to clean and disinfect objects that have been in contact with an infected dog to avoid exposing other canines to the virus. Likewise, people who have been in contact with an ill dog should wash their hands and clean their clothing to avoid spreading the virus. The virus can remain viable on surfaces for up to 48 hours, on clothing for 24 hours, and on hands for 12 hours.

Most dogs exposed to canine influenza virus become infected, with approximately 80% developing clinical signs of disease. Although most dogs recover without incident, some deaths have been reported.

Diagnosing Canine Flu

While canine flu resembles other respiratory illnesses, especially kennel cough, and can be suspected based on clinical signs or the confirmed presence of the virus within the community, testing is needed to confirm the diagnosis.

At present, the most reliable way to diagnose canine influenza is through blood tests taken several weeks apart. However, the virus can also be detected on swabs from the nose. Treatment must begin while awaiting lab results, as it’s generally expected that the tests will confirm the diagnosis rather than make the initial diagnosis.

Treatment and Prevention

Treatment: With canine flu, treatment is typically supportive, and includes fluid therapy and antibiotics as needed to prevent/treat secondary bronchopneumonia. From a holistic perspective, immune support is critical. Maintaining adequate blood levels of vitamin D3 (via lab testing) may reduce the chance of infectious disease (e.g. canine flu) as well as inflammatory and cancerous diseases. Vitamin C has a long history of providing antioxidant and immune support for viral diseases, so adding vitamin C to the treatment protocol may be helpful. Anti-infectious and immune-supporting herbs such as Oregon grape, goldenseal, Echinacea, marshmallow, astragalus, cat’s claw, ginger, lemon balm, oregano leaf, and olive leaf are among my favorites.

Anti-infectious and immune-supporting herbs such as Oregon grape, goldenseal, Echinacea, marshmallow, astragalus, cat’s claw, ginger, lemon balm, oregano leaf, and olive leaf are among my favorites.

Prevention: The best way to protect your dog from contracting canine flu is to ensure he has a healthy immune system (wholesome diet, adequate exercise, minimal stress, minimal toxin exposure, etc.) and to keep him away from other dogs as much as possible if and when canine flu is active in your area.

Facts About Canine Flu

  • Dog flu tends to be a rare disease that moves slowly through the canine population.
  • Risk factors include having dogs in closely confined conditions such as in boarding kennels, daycare settings, and animal shelters.
  • The morbidity rate (percentage of dogs becoming ill if exposed to the virus) can be high (60% to 80%).
  • The mortality rate is very low, especially if aggressive treatment is begun at the first signs (prolonged treatment can be expensive, so I always recommend pet insurance to help cover unexpected expenses such as this). Death occurs mainly in dogs with a severe form of disease (pneumonia or septicemia).
  • Supportive care, antibiotics when needed, and immune-supporting supplements such as vitamin D3 ensure the best chance of cure.
  • Most dogs recover from canine influenza within two to three weeks.
  • Secondary bacterial infections, pneumonia, dehydration, or other health factors (e.g. pre-existing pulmonary disease, immunosuppression, tracheal collapse, etc.) may necessitate additional diagnostics and treatments.
  • To prevent transmission of the virus, dogs infected with canine flu (as well as other dogs in the household) should be kept away from other dogs for at least four weeks.

Should You Consider Canine Flu Vaccination?

Vaccination is available for both strains of dog flu. It can decrease the risk of a dog contracting canine influenza. As in people, the vaccine may not prevent an infection, but it may reduce the severity and duration of illness. The canine flu vaccine (two initial doses are given three or four weeks apart, with annual revaccination if needed) can be administered to healthy dogs that are more than six weeks old. Vaccinated pets are less likely to develop lung lesions, and will be contagious for fewer days.

However, the canine influenza vaccine is not recommended or needed for most dogs. In general, the vaccine is intended to protect dogs at risk for exposure to the virus, which includes those that participate in activities with other dogs or are housed in communal facilities (boarding and training facilities), particularly where the virus is prevalent. Consulting with your veterinarian can determine the risk of exposure and if vaccination is appropriate (in my practice, exposure is so unlikely that vaccination is not needed for my current patients).

Though it can be a serious disease, canine flu is relatively rare, and most dogs recover with prompt treatment.