Genetic testing has confirmed that the ongoing canine influenza outbreak centered in the Chicago area is due to a new strain of canine influenza virus never before seen in the United States, according to Cornell University researchers.
The testing “confirms that an Asian H3N2 virus is circulating,” Cornell officials said in a prepared statement. “All eight genome segments of the virus match closely (99% identity) with viruses isolated from dogs and cats from South Korea. This suggests that the virus likely came from this geographic region, but not necessarily from South Korea.”
The testing was done at the National Veterinary Services Laboratories (NVSL) in Ames, Iowa.
Although all prior cases of canine influenza in the United States have been caused by an H3N8 strain, the genetic testing of the Chicago-area sample “shows no evidence of reassortment” – or mixing – “with Canine H3N8 viruses or any North American H3N2 avian influenza viruses,” the Cornell statement said. “The Asian-origin canine H3N2 influenza virus is also distinct from human seasonal A(H3N2) influenza viruses.”
It remains unclear whether vaccinating pets with existing canine influenza vaccines – which were developed to combat the H3N8 strain previously identified in the United States – will provide any cross-protection against the new virus strain.
It also remains unclear how the new strain arrived in the United States. Cornell officials had said in a press release on April 12 that the Chicago-area outbreak “suggests a recent introduction of the H3N2 virus from Asia.”
Meanwhile, news reports indicated that the outbreak now includes cases in four states: Illinois, Indiana, Wisconsin and Ohio. These reports have not been confirmed by the AVMA.
We are keeping our canine influenza resources updated to reflect ongoing developments, and we will also post updates on our social media channels, including Facebook, Twitter, Google+ and LinkedIn. AVMA members who would like to receive email updates of important news related to animal and public health, such as this discovery, can sign up to do so in our email subscription center.
Anyone with concerns about their pet’s health, or whose pet is showing symptoms of canine influenza, should contact their veterinarian. Symptoms of the disease may include a soft, moist cough or dry cough similar to that induced by kennel cough; discharge from the nose or eyes; sneezing; lethargy; low-grade fever; and loss of appetite.
Additional AVMA resources on canine influenza include the following: