Fielding D. O’Niell, DVM, MS
During my post graduate studies in Virology, my dissertation had to do with Influenza. I'd like to share some information with you. Influenza viruses are of particular interest because they have world-wide distribution, they spread rapidly among host populations, they infect many different species and they are constantly changing.
Most viruses have a single strand of DNA or RNA. Influenza viruses are unique in having 8 separate strands of RNA. If a host is co-infected with 2 different types of influenza, there may be a mis-match of these RNA strands during viral replication and assembly. This reshuffling of the "deck of cards" is termed "Antigenic Shift" and may result in a brand new strain of influenza - a strain potentially capable of causing severe disease in a new host that has no prior immunity. This cyclic "Antigenic Shift" occurs every 10 to 20 years. Most have minor impact but some result in the strain that caused the devastating human pandemic of 1918 which killed 50 million people.
In 2004, a new respiratory disease appeared among racing greyhounds. Infected dogs coughed up blood and died at an alarming rate. This "hemorrhagic fever" was discovered to be a novel strain of Equine Influenza (H3N8) that had undergone Antigenic Shift. It spread rapidly across the nation and we quickly developed a vaccine against this H3N8 strain.
Many infected dogs show no symptoms. Of those that do show symptoms, most will recover, but a few develop a secondary pneumonia. Antiviral therapy such as "Tamiflu" does not appear to be effective. All we can provide is supportive care, such as IV fluids and oxygen while the virus runs its course. Despite our best efforts, a small percentage of infected dogs will die.
This cyclic event of Antigenic Shift has happened again. A novel strain of influenza (H3N2) has emerged among dog populations across the mid-west. Chicago alone reports over a thousand dogs infected with six deaths and counting. This new strain,H3N2, appears to have migrated from Thailand, South Korea or Southern China where it was reported that cats were also affected.
There is a vaccine for both of these strains . Dogs that go to boarding, grooming or day-care facilities, as well as, those that show or compete, should have this vaccine. The first vaccine must be boosted two weeks later and then once annually. If your dog fits this risk category, please call for an appointment.
Let's all hope that this doesn't "go viral" like the major pandemic of 1918.