A Dog Owner’s Guide to Canine Flu

Posted on Jan 11th, 2018, 04:22 AM America/Los_Angeles

A Dog Owner’s Guide to Canine Flu

By Tiffany L. Mitchener, DVM


What is Canine Flu?

There are two subtypes of flu currently infecting dogs in the United States.  The first appeared in January 2004 among racing greyhounds at a racetrack in Florida; H3N8 was originally an equine flu virus which genetically adapted to infect dogs.  It gained the ability to infect dog-to-dog and quickly spread across the United States.

In spring 2015, Chicago became ground zero for another dog flu outbreak.  Veterinary officials originally thought it was another H3N8 outbreak.  Further testing showed that this outbreak was due to a new canine influenza virus H3N2.  This virus was first identified as an avian flu that adapted to infect dogs in South Korea in 2007.  The source of the Chicago outbreak has never been identified.  Nevertheless, it infected over 1000 dogs in the upper Midwest and within five months had spread to 23 states.

The current H3N2 flu outbreak resurfaced in early June 2017. The source of the outbreak appears to be two dog shows, in Florida and Georgia.  It quickly spread throughout the southeastern United States and to Minnesota.  Unfortunately, it has continued to spread, and as of January 2018, new cases of canine influenza H3N2 have been confirmed in the greater Bay Area.  Because H3N2 is a brand new influenza virus to our canine population, all dogs are considered susceptible.


Who can become infected?

All dogs appear to be susceptible regardless of age or breed.  Neither canine influenza type has been shown to infect humans.  Interestingly, during the Chicago outbreak, it was demonstrated that H3N2 could in rare circumstances infect cats and cause a similar disease.


What are the symptoms of the canine flu?

Canine flu has symptoms very similar to the human form of influenza.  In most cases, dogs are feverish, lethargic, and sneezing.  They have decreased appetite, eye and nose discharge, and a soft, moist, persistent cough.  Puppies, senior dogs, and those who are immunocompromised are most at risk of developing more serious infections.  In these cases, dogs can develop high fevers and life-threatening pneumonia.


Can my dog get the flu?

In an outbreak, canine influenza can reach nearly 100% infection rates among those animals exposed to the virus.  Symptoms usually develop 2-3 days after initial infection.  Eighty percent of infected dogs show mild symptoms, and most dogs recover fully in 2-3 weeks.  Infected animals continue to shed virus for up to 24 days with the H3N2 virus, making quarantine an important tool used by veterinarians to control an outbreak.


How does the flu virus spread?

The canine influenza virus is highly contagious.  It can be spread through direct contact, like coughing, barking, and sneezing.  Dogs who are exposed to high dog density situations, like animal shelters, dog shows, dog parks, grooming facilities, and dog day care are considered most at risk.

Canine flu can also spread via indirect contact, meaning that the virus can live on other surfaces, like clothing, toys, floors, food and water bowls, and spread disease for up to 48 hours.  Most frighteningly, a dog owner can unknowingly spread the flu to his own dog by petting an infected dog, then petting his own dog.  The virus can live on human hands for up to 12 hours.  Practicing good hygiene and washing hands with soap and water between petting animals is essential.


What should I do if I think my dog has the flu?

If your dog is showing signs of respiratory disease, a veterinary examination is highly recommended.  Most dogs recover with rest and supportive care; however, some dogs will require hospitalization.  Due to the highly contagious nature of this disease, it is recommended that any dog suspected of having the canine flu be quarantined at home away from other dogs for at least 28 days.


Is canine flu in California?

In March 2017, canine flu H3N2 was discovered in dogs who were imported to Los Angeles from Asia and not properly quarantined.  The virus has continued to occur sporadically in California.  In January 2018, the first documented cases of H3N2 were found in the greater Bay Area leading to our current outbreak.


Is there a vaccine available?

A bivalent vaccine offering protection for both canine influenza subtypes H3N8 and H3N2 is available.  Two doses are recommended for an appropriate immune response; these doses should be given three weeks apart.  It is recommended to continue to booster this vaccine on an annual basis.  It is important to discuss your dog’s lifestyle and risk factors with your veterinarian to determine if he should be vaccinated against the canine flu.


My dog was vaccinated today – is he immediately protected?

It is important to note that it takes time for an animal’s immune system to mount an immune response to a vaccine.  In general, it takes two weeks for a dog’s body to develop protective immunity from a vaccination.  Since the canine influenza vaccine requires a second booster vaccine three weeks after the initial injection, a dog is not considered protected until two weeks after the booster injection or five weeks after the initial injection.  Dog owners should continue to take necessary precautions with potential exposure throughout this period.


My dog received the canine influenza vaccine series – why is he showing signs of a respiratory illness?

Unfortunately, there are multiple disease-causing microorganisms, both bacterial and viral, that can cause respiratory disease in dogs.  Dogs infected with these different pathogens will often show very similar clinical signs of fever, lethargy, sneezing, coughing, eye or nasal discharge.  It is very difficult for the veterinarian to determine the cause of the dog’s symptoms.  Additionally, the canine influenza vaccine, much like the human influenza vaccine, is not 100% effective.  Vaccinated dogs can still develop the disease though usually the course of the disease is milder and shorter than unvaccinated dogs.  Owners of both vaccinated and unvaccinated dogs should take care to avoid high risk situations (grooming facilities, kennels, dog parks, dog daycare, etc.) during an outbreak. 


How can I prevent my dog from getting the dog flu?

  • Avoid close contact with dogs outside the household, especially if dogs have been coughing, sneezing, or have a recent travel history.
  • Do not allow your dog to share food and water bowls, toys, blankets, or leashes.
  • Practice good hygiene among all human family members; remember to wash your hands with soap and water after touching another dog before petting your own dog.
  • Discuss with your veterinarian if vaccination would be recommended for your dog.

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