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About Canine Influenza Virus (Canine Flu)

SITUATION: Researchers report that outbreaks of canine influenza virus, which causes an acute respiratory infection, have been identified in dogs in shelters, humane societies, boarding facilities and veterinary clinics in throughout the USA.

This highly contagious virus is a newly emerging respiratory pathogen in dogs and causes a clinical syndrome that mimics “kennel cough.” Canine influenza virus infections are frequently mistaken for infections due to the Bordetella bronchiseptica/parainfluenza virus complex.

CLINICAL SIGNS: Because this is a newly emerging pathogen, alt dogs, regardless of breed or age, are susceptible to infection and have no naturally acquired or vaccine-induced immunity. Virtually all exposed dogs become infected. Nearly 80 percent have clinical signs. There are two general clinical syndromes - the milder syndrome and a more severe pneumonia syndrome. The milder disease syndrome occurs in most dogs.

In the milder disease, the most common clinical sign is a cough that persists for 10 to 30 days despite therapy with antibiotics and cough suppressants. Most dogs have a soft, moist cough, while others have a dry cough similar to that induced by Bordatella bronchiseptica/parainfluenza virus infection. Many dogs have purulent nasal discharge and a low-grade fever. The nasal discharge likely represents a secondary bacterial infection that quickly resolves with treatment with a broad-spectrum, bactericidal antibiotic.

Some dogs develop a more severe disease with clinical signs of pneumonia, such as a high fever (1 040F to 1 060F) and increased respiratory rate and effort. Thoracic radiographs may show consolidation of lung lobes. Dogs with pneumonia often have a secondary bacterial infection and have responded best to a combination of broad-spectrum, bactericidal antibiotics and maintenance of hydration with intravenous fluid therapy.

FATALITY RATE: Fatal cases of pneumonia have been documented, but the fatality rate so far is at 1 percent to 5 percent.

INCUBATION/SHEDDING PERIOD: The incubation period is two to five days after exposure before clinical signs appear. Infected dogs may shed virus for seven days from the initial day of clinical signs. Nearly 20 percent of infected dogs will not display clinical signs and become the silent shedders and spreaders of the infection.

PREVENTION: There is no vaccine for canine influenza virus at this time. This virus is spread by aerosolized respiratory secretions, contaminated inanimate objects and even by people moving back and forth between infected and uninfected dogs. This is an enveloped virus that is most likely killed by routine disinfectants, such as quaternary ammoniums and dilute bleach. Because the virus is highly contagious and all dogs are susceptible to infection, veterinarians, boarding facilities, shelters and pet stores should use isolation protocols for dogs that have a “kennel cough.”

Dog Flu Facts

• The H3N8 influenza virus has jumped from horses to dogs
  
  
• This H3N8 virus causes ‘dog flu’
  
  
• Initial findings of H3N8 infected dogs were at a Florida greyhound racing track
  
  
• The H3N8 virus causes symptoms that mimic traditional ‘kennel cough’
  
  
• ‘Kennel cough’ is typically caused by bordatella bronchiseptica bacterium
  
  
• Other symptoms of H3NB infection are nasal discharge and fever
  
  
• Both H3N8 and bordatella are contagious between dogs
  
  
• Dogs diagnosed with H3N8 infection should be isolated
  
  
• Approximately 80% of H3NS infections will be mild
  
  
• A small minority of infected dogs may experience complications such as pneumonia
  
  
• A small minority of infected dogs will also be asymptomatic and will not show any signs of the infection. However, it is believed that asymptomatic dogs are infectious
  
  
• The H3N8 virus has never infected humans
  
  
• H3N8 causes a morbidity rate of 5 to 8% in infected dogs
  
  
• There have been verified occurrences of H3NB in dogs in South Florida shelters boarding facilities and veterinary clinics
  
  
• H3N8 has also been verified in New York City and Massachusetts
  
  
• If a pet dog exhibits coughing, nasal discharge or fever, the dog should be treated by a veterinarian as soon as possible
  
  
• Dog owners that have a dog that recently had a respiratory infection should keep their dogs home for a couple of weeks after the illness as to not infect other dogs

The above information was condensed from a transcript from
a Centers for Disease Control media teleconference on September 26, 2005

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