Two years ago we had an outbreak of canine influenza in the Chicago area. Over 9,000 dogs developed the disease and the country was surprised to later learn that this outbreak was caused by a strain of canine influenza never before seen in the United States. Canine influenza was first recognized in Florida in 1995 and the causative agent was H3N8. Affected dogs develop severe respiratory signs, ocular and nasal discharges and high fevers. The disease is highly contagious and although most dogs recover from the virus, they are very sick for quite some time before they begin to improve. The disease is so highly contagious because infected dogs may be shedding the virus before they become ill themselves and the virus can linger on human hands and clothing for up to 24 hours during which time people often travel and have contact with yet more dogs. During the Chicago outbreak, unlike the H3N8 of the past outbreaks, officials isolated the H3N2 virus. It is believed that this virus entered the United States in a group of rescue dogs that had been destined for meat production in other countries. Unfortunately, the virus spread like wildfire in the Chicago area and the past vaccination which had been developed to prevent the H3N8 virus did not offer cross production of this new virus isolate. It took several months before outbreaks in the Chicago area began to slow down.
Florida recently announced yet another outbreak of canine influenza in the central Florida area. This was first determined to be H3N2, the new virus, but since then cases of H3N8 have also been confirmed so it appears that both strains are present in this current outbreak. The virus has also recently been confirmed in Georgia, South Carolina, Kentucky, Illinois, North Carolina, Tennessee, and Texas in recent days. Although Indiana has so far remained off of the list, we are bordered by Illinois and Kentucky and anticipate this virus could spread quickly through our state as well.
Since the Chicago outbreak, an additional vaccine was made to protect from the H3N2 strain and a new bivalent vaccine is now available that will cover both strains in the same vaccine. It is our recommendation that any pets at risk be vaccinated with this bivalent vaccine. The initial dose should be boostered in 2-4 weeks after the first dose to provide full immunity and then repeated annually. Unfortunately, unlike other vaccines, the immunity does not last much beyond a year and any pet that is more than 12 weeks overdue for the annual booster should have the initial 2 series boosters repeated to ensure full protection.
It is always best to consult with your veterinarian about your pet’s health and risk factors for contracting diseases such as canine influenza.