Canine flu

SITUATION: University of Florida 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 Florida; predominantly in Broward, Dade, Palm Beach and Duval counties. 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.

Wednesday, 24 August 2005
Veterinary Advisory – August 16, 2005

update August 2006 DVM Newsmagazine
-canine influenza now confirmed in 22 states
-16% infection rate, 7% mortality rate; affecting veterinary practices as well as shelters

CLINICAL SIGNS: Because this is a newly emerging pathogen, all dogs, regardless of breed or age, are susceptible to infection and have no naturally acquired or vaccine-induced immunity. Virtually 100% of exposed dogs become infected. Nearly 80% 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 21 days despite therapy with antibiotics and cough suppressants. Most dogs have a soft moist cough, while other have a dry cough similar to that induced by Bordetella 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 (104ºF to 106ºF) 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 low (1-5%).

INCUBATION / SHEDDING PERIOD: The incubation period is 2-5 days after exposure before clinical signs appear. Infected dogs may shed virus for 7-10 days from the initial day of clinical signs. Nearly 20% 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 10% 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 are presumed to have “kennel cough”.

FOR MORE INFORMATION: Contact Dr. Cynda Crawford in the Dept of Small Animal Clinical Sciences at the University of Florida Veterinary Medical College for sample submission via phone (352-392-4700, ext 5731), fax (352-392-6125), or email (