A dangerous dog flu has turned up this year in 8 states. It can hit dogs of any breed, age or health. H3N2 canine influenza virus was first seen in the US in 2015 and already has affected thousands of dogs. It is highly contagious, though it is not known to be transferable to humans. The virus can survive in the environment—including kennel surfaces, food and water bowls, collars and leashes, toys and beds—and on people’s clothing for up to 24 hours before the virus dies.

Common symptoms of H3N2 include sneezing, nasal discharge and frequent coughing, and can last for two weeks or more. Many dogs also develop fever, decreased appetite and general lethargy in the first few days of the illness. Those at greatest risk are ones with a social lifestyle or those in kennels, day-care centers, shelters, dog shows, veterinary clinics, grooming parlors or any other group facilities. Dogs that mostly stay at home and walk only around their neighborhood are at low risk.

If your dog develops symptoms, call your veterinarian but do not take your dog to the animal hospital—that can spread this disease. Similar symptoms may be caused by a virus other than H3N2—a veterinary diagnostic test is needed to find out. Follow your vet’s instructions carefully. Animals with H3N2 usually recover at home without complications in about two weeks. But they still may remain contagious for four weeks and therefore must be kept isolated from all other dogs for four weeks. And in some more serious cases, dogs develop life-threatening pneumonia and must be hospitalized.

Cats also can become infected. They usually have the sneezing and nasal discharge but not the cough. All cats and dogs living together must be quarantined for four weeks if any one of them comes down with H3N2 canine influenza. In addition, owners need to kill the virus on anything that can harbor it by washing their hands with soap and water, laundering clothing and bedding, and washing food and water bowls and toys with soap and water. There is a vaccine available to protect dogs from canine flu. Contact your veterinarian for details. The best way to protect cats from contracting the illness is to keep them isolated from dogs that have become infected with the virus.