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Canine Influenza - Helpful information for pet owners

Posted by: Jeremiah Saliki, DVM, PhD, DACVM and Amie Koenig, DVM, DACVIM (SAIM), DACVECC*

UPDATE: July 14, 2017

  • As of July 14, 2017, we are aware of fifteen confirmed cases of Canine influenza
    from six Georgia counties. These numbers include samples tested in our Veterinary Diagnostic Laboratories lab as well as two other labs which tested samples from Georgia. The locations of these confirmed cases are in the following counties: Brantley (1), Bryan (1), Burke (1), Cherokee (1), Jasper (10), Toombs (1). As a caveat, we do not have complete information on samples tested in out-of-state labs to which samples from Georgia might have been sent. Therefore, it is possible that the number of positive cases is higher than 15.

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UPDATE: June 14, 2017

  • As of June 14, 2017, we are aware of fourteen confirmed cases of Canine influenza from five Georgia counties. These numbers include samples tested in our Veterinary Diagnostic Laboratories lab as well as two other labs which tested samples from Georgia. The locations of these confirmed cases are in the following counties: Brantley (1), Burke (1), Cherokee (1), Jasper (10), Toombs (1).

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What is the current situation of canine influenza in Georgia?

  • As of May 31, 2017, the Athens Veterinary Diagnostic Laboratory and at least two out-of-state laboratories have confirmed about 10 recent cases of canine influenza in dogs from Georgia. Some of these cases have been typed and determined to be caused by the H3N2 subtype. All positive Georgia cases came either from dogs that just returned from the May 19-21 Perry, Ga., dog show or had been in contact with such dogs. Recent cases of H3N2 canine influenza have also been reported in FL, IL, KY, MI, MO, and NC.
  • Canine influenza, H3N2, was initially documented in the US in 2015 when it was associated with an outbreak of canine respiratory disease in the Chicago area. Between May-August 2015, hundreds of dogs in Georgia were also confirmed to be affected by H3N2. Other subtypes of canine influenza include  H3N8, which was first documented in dogs in North America in 1999, and H5N2, which is currently limited to China.

Can these viruses be transmitted to other animals or to people?

  • All influenza viruses are prone to changing over time (termed “antigenic shift”) and adapting to new hosts or becoming more pathogenic in their current hosts. This is likely the mechanism by which the H3N8, H3N2, and H5N2 strains became adapted to dogs. It is conceivable that in the future other strains may emerge in dogs.
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  • Currently, there is no documentation of dog-to-human spread of H3N8, H3N2 or H5N2. The H3N8 type of influenza has been endemic in horses in the United States since at least 1963 and horses are the suspected source of the type of H3N8 influenza we now see in dogs. There are no documented cases of H3N8 transmission from horses to humans. The H3N2 subtype of canine influenza has been shown to infect cats in shelter settings, but it is not yet clear how likely this is under normal household circumstances. H3N2 has been documented in cats in a shelter in Indiana. Influenza H7N2 was documented in a large outbreak in 2016 in cats, but not in dogs, in a shelter in New York City. We encourage pet owners with sick animals to be diligent about washing their hands, as well as their pet’s bedding, bowls, toys, etc.

What dogs are at risk of contracting canine influenza?

  • All dogs are at risk of contracting canine influenza, but those that have not been vaccinated against the virus are at a higher risk. Current evidence suggests that at least 80% of healthy dogs of all ages exposed will contract the flu. The incubation period for the onset of clinical signs is 2 to 4 days after exposure. However, dogs can shed the virus during this incubation period, thus contaminating in-contact dogs before the first signs of disease appear. About 25% of dogs exposed to the virus do not show any clinical signs, but they may still shed the virus and infect other dogs who may become sick. Dogs infected with H3N2 can shed the virus for up to 26 days and should be isolated from unexposed dogs for a minimum of 21 days.
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  • The dogs most at risk of serious illness and/or other complications from the infection are the very old, the very young, or those that have been previously unhealthy or have a chronic condition (e.g., dogs undergoing treatment for cancer, or that have diseases that suppress the immune system, or that require immune-suppressive medications such as prednisone for chronic conditions, those with chronic lung or airway diseases, etc.).

How does canine influenza spread?

  • Like other respiratory illnesses, canine influenza spreads through respiratory secretions — droplets of mucus, from sneezing or coughing, that aerosolize in the air and settle on surfaces. The virus does not remain alive for long in the environment, and it can be easily killed by common disinfectants. Canine influenza lives up to 48 hours on surfaces in a climate‐controlled environment, a shorter time outside in the sun and heat, and it may survive up to 12 hours on unwashed skin and up to 24 hours on clothing.
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  • Just like when people contract the flu, pet owners with sick dogs should be diligent about washing their pet’s bedding, toys, food and water bowls, and other surfaces that may come into contact with your animal. You can disinfect bedding and other items by washing them in common disinfectants, including bleach and quaternary ammonium compounds (QACs or Quats). Most Lysol products have benzalkonium chloride as an active ingredient, which is a QAC. There are also commercial or hospital versions of these products, which contain higher concentrations of these compounds.

What are the typical symptoms of canine influenza?

  • As noted above, the majority of dogs will show clinical signs of the disease within 2 to 4 days after exposure to it, and these dogs will shed virus during the incubation phase of the illness. About 25% of exposed dogs will not show clinical signs, but they can shed the virus, meaning they can infect other dogs.
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  • The typical clinical signs are fever, coughing, sneezing and lethargy, which are indistinguishable from more classic causes of canine infectious tracheobronchitis, also known as “kennel cough” or ITB. Things to watch for that may point to canine influenza include a rapid spread of infection through a population of otherwise healthy and/or vaccinated adult dogs, and potentially higher rates of fever.

If my dog contracts canine influenza, how is the disease likely to progress?

  • Most dogs will recover within 2 to 3 weeks after the onset of clinical signs of the illness. In most cases, the illness will resolve without treatment, though some dogs will need supportive care (e.g., fluids or therapeutics as prescribed by a veterinarian). Very old dogs, very young dogs, and dogs that have been recently unhealthy or that are under treatment for chronic disease are the dogs at greatest risk of complications from canine influenza. The most dangerous complication would be pneumonia.

Can my dog die from canine influenza?

  • The majority of dogs that contract the disease will recover from it, but a small percentage will die from canine influenza. Current available data suggests that 1 to 5% of dogs that contract H3N8 will die from the disease or from complications that arise from the disease. While the recent Chicago outbreak garnered a lot of media attention, there is no evidence that the H3N2 strain responsible for this outbreak is more severe than the H3N8 strain that has circulated in North America since 1999. If popular press reports about the 2015 Chicago outbreak are accurate, more than 1500 dogs were diagnosed with H3N2, and 6 deaths were reported, which would equal a survival rate of approximately 99.6%.

Should my dog be vaccinated for canine influenza, and if it is, will the vaccination protect against H3N8 and H3N2?

  • Individual vaccines are available for canine influenza H3N2 and H3N8 and a bivalent vaccine, containing both of these subtypes, has recently come on the market. Canine influenza vaccination is considered a “non-core” vaccine and is recommended for socially active dogs, such as those that travel, are boarded with other dogs, or are exposed to dog shows or dog parks. The risk factors for Bordetella infection and canine influenza are the same and it only takes a single infected dog to bring the virus into a new area. Consult a veterinarian for more information about the vaccination and to decide if your dog has a lifestyle that would support administration of the vaccine.

Are the other animals in my house at risk?

  • The H3N2 strain of canine influenza has been shown to infect cats in shelter settings, but it is not yet clear how likely this is under normal household circumstances. We do encourage pet owners with sick animals to be diligent about washing their hands, as well as their pet’s bedding, bowls, toys, etc. to prevent contamination of objects and inadvertent spread among animals.
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  • Various species of wild birds are permissive hosts of many strains of influenza, meaning that they can harbor more than one strain of the virus and allow antigenic shift to occur. Oftentimes, the birds themselves do not exhibit signs of the flu that they are carrying. H3N8 has not been known to infect poultry or other birds and it is also unknown if the canine-adapted strain H3N2 can infect pet birds.

Where can more information about canine influenza in Georgia be obtained?

  • The UGA Veterinary Diagnostic Laboratories in Athens and Tifton are the official veterinary diagnostic labs for the state of Georgia and are closely following the current cluster of canine influenza cases in Georgia and other states. As of this writing, there have been three confirmed cases of canine influenza at the Athens Veterinary Diagnostic Laboratory for samples submitted during the last week of May 2017 from dogs that had just returned from the Perry, Ga., dog show. In order to rule in or out canine influenza as well as the many other pathogens that can cause respiratory disease in dogs, the recommended laboratory test is the Canine Respiratory PCR Panel. For information on cost, turn-around time, and samples to submit, veterinarians can refer to https://adlab.vet.uga.edu/LabPortal/catalog/show/403 or call 706-542-5568.
  • For more information about canine influenza virus, vaccination, or whether your dog should be vaccinated, contact your veterinarian. If you believe you have a dog that may have become infected with canine influenza virus, contact your veterinarian. You may also find information on the American Veterinary Medical Association’s website at https://www.avma.org/Search/results.aspx?k=canine%20influenza

*This article is an updated version of the information sheet that was created by Kate Creevy, DVM, MS, DACVIM and Jeremiah Saliki, DVM, PhD, DACVM on 5/21/201.