Animal shelters have been among the places hardest-hit with infections of the H3N2 canine influenza virus since it made its first U.S. appearance in dogs from a Chicago animal shelter. Understanding how to prevent the spread of this respiratory disease is critical to protecting dogs in shelters and the community. One key to preventing transmission is to isolate infected dogs, but for how long?

Researchers at the University of Wisconsin conducted a review of the medical records of 16 dogs from three Chicago-area shelters who had been naturally infected with the virus. Their intention was to see if the recommendation for eight days of isolation was sufficient, or if dogs continued to shed the virus beyond that time period. The shedding of virus is a key component to the spread of the disease.

After reviewing the records and conducting tests on samples that had been taken from the infected dogs, the authors concluded:

Documentation of the extended shedding period of canine influenza A H3N2 virus in the affected dogs of the present report helps to explain, at least in part, why such a large number of dogs were affected by H3N2 infections in this outbreak, as prolonged shedding increases the likelihood of exposure.

These data and anecdotal information reported by shelters affected by H3N2 virus suggest that, to reduce the risk of transmission of H3N2 virus, infected dogs should be isolated from uninfected, unexposed dogs for a period of (greater than or equal to) 21 days following onset of illness.

The study was published in the Journal of the American Veterinary Medical Association, which has made it available in its entirety for no cost at the link below.

Sandra Newbury, Jennifer Godhardt-Cooper, Keith P Poulsen, Francine Cigel, Laura Balanoff, Kathy Toohey-Kurth; Prolonged intermittent virus shedding during an outbreak of canine influenza A H3N2 virus infection in dogs in three Chicago area shelters: 16 cases (March to May 2015).J Am Vet Med Assoc 2016 May;248(9):1022-6

Also of interest:

What animal shelters need to know right now about the new canine influenza