A New Strain of Canine Flu Is on the Rise

Your dog can get the flu, and just not from you. Since April, a strain of canine specific influenza is popping up in various states. 

In April, an outbreak in Chicago infected close to 1,000 dogs. Since then, Cornell's Animal Health Diagnostic Center says that cases have emerged in 11 additional states: Alabama, California, Texas, Massachusetts, New York, Wisconsin, Michigan, New Jersey, Iowa, Indiana and Georgia. USA Today's Lori Grisham reports a case in Ohio, as well, putting other states and pet owners on alert.

Before fearing for Fido's life, there are a few key things to know about this strain and dog flu in general. The virus spreads from nose to nose between dogs, and symptoms look much like the flu in humans: Fever, lots of snot, coughing and fatigue. The way dog flu spreads is not unlike "how respiratory disease spreads at a daycare or airport — people sneezing and coughing on each other," Keith Poulsen, a veterinarian at the University of Wisconsin at Madison, told USA Today.

They share the same name, but this viral strain is different from the seasonal H3N2 flu virus that infects humans. Researchers do sometimes worry about flu strains spreading from humans to pets and vice versa, as Smithsonian's Joey Stromberg reported in 2012, but that's not what's going on here. In fact, this version of H3N2 has shown no ability to infect humans, as the Centers for Disease Control said back in April.

H3N2 is actually a strain of bird flu that can pass between dogs and cats, perhaps guinea pigs and ferrets, as well. Scientists suspect the strain emerged in Asian bird markets before adapting and making the jump between species. In 2007, the viral strain first showed up in dogs in South Korea, but has also infected dogs in China and Thailand.

However, H3N2 isn't the first strain of dog flu to emerge stateside. A strain called H3N8 has been infecting canines here since 2009. The virus had been prevalent for 40 years in horses before spreading to dogs. There is a vaccine for the H3N8 strain, but some key genetic differences between the strains suggest it will not be incredibly effective against H3N2.

Just like with people, very young dogs and very old dogs are most susceptible, but most recover. Though the numbers point to the virus spreading, don't panic. Vets suspect that the fatality rate for dog flu is very low — possibly as low as two or three percent of cases.

Helen Thompson | | READ MORE

Helen Thompson writes about science and culture for Smithsonian. She's previously written for NPR, National Geographic News, Nature and others.