Canine Influenza Virus or CIV

What is canine influenza?

Canine flu is a contagious respiratory disease in dogs caused by a specific Type A influenza virus referred to as a “canine influenza virus.”  This virus is very contagious among dogs but is not transmitted to humans or other household pets such as cats and birds.

What causes canine influenza?

The “canine influenza virus” is an influenza A H3N8 influenza virus (not a human influenza virus) that was originally and equine (horse) influenza virus.  This virus has spread to dogs and now spreads rapidly between infected dogs.

How serious is this infection?

The number of dogs that die from canine influenza virus is very small, only from 15% of cases.  Some dogs have no symptoms (20%), while some have mild to severe infections (80%).  Severe illness is characterized by the onset of pneumonia. Although this is a relatively new cause of the disease in dogs and nearly all dogs will have mild form of disease and the rest will show no signs at all of infection even though they are still contagious.

Transmission

Canine influenza is spread via aerosolized respiratory secretions and contaminated objects (kennel surfaces, food, water bowls, collars, and leashes) and people moving between infected and uninfected dogs.  The virus can remain viable on surfaces for up to 48 hours, on clothing for 24 hours, and on hands for 12 hours.  The virus is easily inactivated by soap and  water, so good hand hygiene and laundering of contaminated items are important methods of preventing spread of CIV.  CIV is most likely to spread in facilities where dogs are densely housed or where there is a high turnover of dogs in and out of the facility.  Dogs in communities where the virus is prevalent are at high risk of contracting CIV when visiting shelters, boarding facilities, canine day care centers, veterinary clinics and pet stores.

Vaccination

In May 2009, the USDA approved the licensure of the first influenza vaccine for dogs developed by Intervet/Schering Plough Animal Health Corporation.  The canine influenza vaccine contains inactivated whole virus so there is no risk of vaccine-induced influenza.

The vaccine is intended as an aid in the control of disease associated with CIV infection.  Although the vaccine may not prevent infection all together, efficacy trials have shown that the vaccination may significantly reduce the severity and duration of clinic illness, including the incidence and severity of damage to the lungs.  In addition, the vaccine reduces the amount of virus shed and shortens the shedding interval; therefore, vaccinated dogs that become infected develop less severe illness and are less likely to spread the virus to other dogs.  These benefits are similar to those provided by influenza vaccines used in other species, including humans.

The canine influenza vaccine is a “lifestyle” vaccine, and is not recommended for every dog.  In general, the vaccine is intended for the protection of dogs at risk for exposure to the CI virus, which in clued those that either participate in activities with many other dogs or are housed in communal facilities, particularly where the virus is prevalent.  Dogs that may benefit from canine influenza vaccination include those that receive the kennel cough (Bordetella/parainfluenza) vaccine, because the risk groups are similar.  Dog owners should consult with their veterinarian to determine whether their dog’s lifestyle includes risks for exposure to the CI virus and if the vaccine is appropriate for their dog.