Flu season is a constant, evolving threat to man – and, now, to man’s best friend.

Outbreaks of a highly contagious canine influenza have been cropping up in New York, New Jersey, Massachusetts, Connecticut, Colorado, Texas, and California. All told, the dog flu has been confirmed in 38 states.

While outbreaks can occur year-round, more cases are likely during the holidays as owners go on holiday and board their dogs, upping the risk of contact with other dogs carrying the virus. A nasal swab or blood test can confirm infection. But, because it is relatively new, dogs have not yet developed immunity to it.

Pharmaceutical giants Merck and Pfizer have come to the rescue of our four-legged friends: they have developed doggie flu vaccines to help prevent infection. Some boarding facilities and vet offices now recommend the dog flu vaccine for all visiting dogs.

Like human flu, symptoms of canine influenza include a persistent cough and a thick nasal discharge. Dogs of all ages are susceptible, but fatality rates are low, according to the American Veterinary Medical Association – about 5 to 8 percent.

First identified in 2004, canine influenza began as a mutated equine flu virus that jumped from horses to dogs. People cannot catch the dog flu, but they can spread it to other dogs.