Pet owners are being told to be cautious about the spread of the H3N8 dog flu. The disease is real and spreading.

A Fairfax County, Virginia, shelter was hit by the virus recently. It killed one dog and made more than two dozen others ill before the center was closed for two weeks.

Since it was first identified in 2004, the H3N8 dog flu virus been found in 30 states and the District of Columbia.

The Canine influenza can't be spread to humans and there is a vaccine that can be given to dogs by veterinarians.

"This is not something dogs can transmit, so there's no worry, no concern over that, so far," says Dr. Anthony Gary with Arkansas Veterinary Internal Medicine.

Symptoms of canine flu in dogs include cough, runny nose and fever.

Pet owners are being warned to be cautious about taking dogs to day care centers, boarding facilities and even dog parks.