AVMA Guidelines for Canine Influenza

http://www.avma.org/public_health/influenza/canine_guidelines.asp

University of Illinois College of Veterinary Medicine

Fast Facts on Canine Influenza

http://www.cvm.uiuc.edu/petcolumns/showarticle.cfm?id=475

Dog Flu
News from the Illinois Department of Agriculture (posted 10/3/05)

A newly emerging respiratory pathogen in dogs has been identified as a virus belonging to the influenza A family.  These viruses can infect humans, domestic animals, (pigs, horses, chickens, ducks), and some wild birds.  The University of Florida College of Veterinary Medicine has isolated and identified H3N8 influenza virus as the cause of a serious respiratory disease in dogs in shelters, humane societies, boarding facilities and veterinary hospitals in Florida. Cases have been predominantly in Dade, Palm Beach and Duval counties.  Racing greyhounds in Florida have also been affected.  There are confirmed cases in New York State.  This particular strain is not known to affect humans or poultry and appears to be a mutated form of the equine influenza virus.

Influenza viruses are defined by membrane proteins that are distinguished by their genetic structures.  These proteins are referred to as H and N.   The H protein has 15 genetic subtypes and the N protein has 9 genetic subtypes.  Very few of the subtypes have consistently circulated among people, (predominantly H1N1, H1N2, H2N2, H3N2), or domestic animals.  Virtually all of the possible influenza subtypes exist among wild waterfowl.  In birds the virus lives and is shed predominantly through fecal contamination.  It is highly contagious among birds; waterfowl are usually asymptomatic but it can be deadly to domesticated birds, such as chickens.  Reassortment of the virus commonly occurs when 2 different subtypes are present in the same animal.  Influenza virus has the ability to change its molecular antigenic structure making previously immune animals susceptible.

This disease in dogs can mimic the kennel cough syndrome caused by Bordetella bronchieptica/parainfluenza virus complex.  Since it is a newly emerging disease virtually 100% of exposed dogs will become infected.  Dogs may remain asymptomatic, exhibit mild illness, or present with severe pneumonia.  Approximately 20% of the dogs will be asymptomatic.  The remaining 80% will develop clinical illness with the majority showing a mild syndrome that presents as a cough with or without a low grade fever.  The cough does not respond to antibiotics or cough suppressants and generally lasts 10 to 21 days.  The cough may be soft and moist or dry.   A purulent nasal discharge may develop which is generally caused by secondary bacterial infection and is responsive to antibiotics.  This presentation is difficult to differentiate from kennel cough syndrome.  Standard treatments for upper respiratory infections should be instituted regardless of the cause. 

The severe pneumonic syndrome presents as clinical pneumonia with high fevers (104 - 106), increased respiratory rate and difficulty breathing.  Thoracic radiographs show generalized pneumonia with consolidation of the lung lobes.  These dogs should be treated symptomatically with broad-spectrum antibiotics for secondary bacterial infections, hydration therapy, and other supportive care as needed.  Mortality in these dogs is 1 - 5%.

No vaccine for canine influenza is currently available.  The use of flu vaccines approved for other species is not recommended because of the potential for adverse and possibly fatal reactions. 

Influenza virus is transmitted by aerosolized respiratory secretions, contaminated inanimate objects (food bowls, dog crates), and people moving from infected dogs to uninfected dogs.  The virus is easily killed with any disinfectant that will kill parvovirus.  The incubation period is 2 - 5 days and dogs can shed the virus for up to 10 days after the onset of symptoms.  All dogs with symptoms of kennel cough or pneumonia should be isolated from other dogs for a minimum of 10 days after onset of symptoms to prevent spread. 

There is no rapid test for canine influenza virus.  Serology is available but antibodies do not develop until 7 or more days after the onset of symptoms.  Convalescent samples 2 or more weeks after the onset of symptoms aid in the diagnosis.  Although canine influenza is not reportable in Illinois, the Illinois Department of Agriculture appreciates the voluntary reporting of laboratory confirmed cases of canine influenza in the state.  This information will be shared with veterinary professionals in Illinois to alert them to the presence of the virus in the state. To date there are no known reported cases of canine influenza in Illinois.