The Idaho Veterinary Medical Association has received reports of dogs testing positive for Canine Influenza in Idaho. Both affected dogs, one in Boise and one in Rigby, are infected with Canine Influenza Virus (CIV) subtype H3N2. The IVMA has also heard reports of two dogs in Salt Lake City positive for CIV subtype H3N8.
Canine Influenza is an emerging disease across the nation. Dogs in the greater Bay Area of California began experiencing an outbreak of CIV H3N2 in December 2017, which has quickly expanded locally and regionally into other states and Canada through adoptions and other forms of movement. CIV H3N8 originally emerged in Florida in 2004 from equine influenza virus and has more slowly expanded across the United States.
Risks for new introductions also come with canine adoptions from Asia, which is believed to be the source of the 2015 H3N2 canine outbreak in Chicago and possibly also the current California outbreak. There are few safeguards in place to keep emerging pathogens from coming into Idaho, particularly for pathogens such as Canine Influenza which are easily transmitted even by animals shedding subclinically.
The IVMA, with input from Idaho Public Health, is recommending proactive vaccination of at-risk dogs for CIV to protect these patients and prevent outbreaks in our communities. Because CIV is readily spread during comingling, vaccination against both subtypes is strongly recommended, at minimum, for dogs that are traveling, boarding, visiting groomers or doggie daycare, frequenting dog parks or dog shows, and shelter dogs. Vaccination should be considered for dogs with cardiac disease, pre-existing pulmonary disease, brachycephalic breeds, and senior dogs. Also, vaccination of veterinary staff dogs is advised, as transmission can occur via fomites (i.e. clothing). Initial vaccination requires a 2-dose series. Full effectiveness does not occur until after the SECOND immunization in the initial series and is effective for 12 months. Bivalent vaccines are available from multiple manufacturers; please follow the manufacturer’s guidelines for revaccination interval. Aggressive disinfection is necessary to keep fomite-associated spread to a minimum. Although Canine Influenza is not a reportable or notifiable disease in Idaho, because of its emerging nature, alerting the IVMA (phone 800-272-1813), Idaho Public Health officials (phone 208-334-5939), or Idaho Department of Agriculture officials (208-332-8540) will help us all monitor its geographic distribution and keep veterinarians advised of developments.
Neither H3N2 nor H3N8 subtypes are currently considered zoonotic; however, influenza viruses are skilled at recombination, so suspect and confirmed cases should be handled with infection prevention (animal and human) in mind. The incubation period is generally 1 – 8 days following exposure. A mild kennel-cough type illness is the most common presentation, but severe pneumonia and even death have been reported for some animals. There have been some reports in the United States and Asia of cats infected with H3N2. Here are some helpful links to learn more:
• Iowa State University provides a comprehensive summary of information on Canine Influenza: http://www.cfsph.iastate.edu/Factsheets/pdfs/canine_influenza.pdf.
• NASPHV provides excellent advice on infection control practices, also useful for non-zoonotic pathogens: http://www.nasphv.org/Documents/VeterinaryStandardPrecautions.pdf
• AVMA has pet owners’ guides and a guidance document for veterinarians:https://www.avma.org/KB/Resources/FAQs/Pages/Control-of-Canine-Influenza-in-Dogs.aspx
• Cornell Animal Health Diagnostic Center compiles data from commercial labs across the country: https://ahdc.vet.cornell.edu/news/civchicago.cfm
Dr. Sherilynn Burkman, One Health Committee Chair, Idaho Veterinary Medical Association
Dr. David Ard, President, Idaho Veterinary Medical Association
In cooperation with Dr. Leslie Tengelsen, Idaho Public Health and Dr. Bill Barton, Idaho Department of Agriculture