By Matthew Kearns, DVM
There has been a lot of media attention recently about outbreaks of the canine influenza virus (CIV), the H3N8 strain, which was first reported in racing greyhounds in Florida in 2004. Rather than the typical respiratory infections (both viral and bacterial) that were limited to mild upper respiratory signs (coughing, sneezing, etc.), many of these dogs developed a sudden onset of severe pneumonia and death.
Later that year similar cases were documented in shelters and veterinary clinics in the New York City area. Dogs that recovered were tested at the Cornell Animal Health Diagnostic Center at Cornell University and tested positive for the CIV H3N8 strain. In 2011, there was another outbreak in the NYC Metro area (three cases in NYC, three in Nassau County but none in Suffolk County) of the CIV H3N8 strain.
Fast forward to 2015 — an outbreak of the CIV occurred in the Chicago area that affected more than 1,000 dogs and led to eight deaths. Another outbreak shortly after the Chicago incident occurred in the Atlanta area affecting approximately 80 dogs (no deaths). In December 2015, another outbreak occurred in the Seattle area affecting approximately 80 dogs (again, no deaths).
Interestingly, none of the cases in 2015 were caused by the CIV H3N8 strain, but rather an H3N2 strain. The H3N2 strain was previously only seen in Asia (first diagnosed in 2006-2007). It is believed that this Asian strain gained entrance to the United States through Chicago’s O’Hare Airport inside a dog from Korea.
CIV is passed from dog to dog via aerosolized respiratory secretions from coughing, barking, sneezing, contaminated objects (food and water bowls, kennel surfaces) and people moving between infected and uninfected dogs. Dogs that stay at kennels, groomers, doggy day care, parks etc. are more at risk.
Approximately 80 percent of dogs exposed to CIV will show symptoms of the disease and the other 20 percent will not. This is unfortunate because this 20 percent may not show symptoms, but they can still shed virus and spread disease. Symptoms will start three to five days after exposure and can be very mild to severe.
Mild symptoms include a low-grade fever, runny nose and cough. Severe symptoms include pneumonia and in some cases death. Risk factors include age (the very young and very old are most severely affected), pre-existing disease or genetic susceptibility. There is no evidence at this time that CIV poses any health risk for humans.
Treatment for CIV is supportive in nature. Less severe cases where the patient is able to eat and drink are self-limiting in nature and symptoms resolve within three to seven days. More severe cases require hospitalization, IV fluids/medications, nebulization treatments and, in some cases, supplemental oxygen.
Two vaccines against the CIV H3N8 strain (the first was approved by the FDA in 2009) are available for dogs at this time. The goal of the vaccine is to expose the host (in this case dogs) to a weakened or inactivated form of the virus and stimulate the immune system to produce antibodies against it. Then, if the host is exposed to the virus naturally, the immune system will respond rapidly and fight the infection before signs of disease will occur.
At this time there is good news and bad news. The good news is there have been no reported cases of either strain of CIV in Suffolk County. The bad news is there is no evidence at this time that the vaccine currently available will protect against the new Asian strain (it may, but the veterinary community just doesn’t know at this time).
Please consult with your veterinarian as to whether your dog is at risk for the CIV virus (H3N8 or H3N2 strain) and whether vaccine is warranted for your own dog. I will keep everyone posted through Times Beacon Record Newspapers as new information becomes available.
Dr. Kearns has been in practice for 16 years.