MARINE PARK, Brooklyn (WABC) -- Veterinarians in New York City are warning dog owners about a dangerous strain of the canine flu that is spreading in the area.Experts say the H3N2 virus has sickened about 500 dogs on the West Coast this year and is believed to be making its way east. Since April, three dozen cases of dog influenza have been reported in Brooklyn, and more recently, a few cases have been reported in Manhattan.Dominick Forte's dog Coconut has been coughing for about a week. On Tuesday he will take her to the vet to be tested for the dog flu, which he never heard about until now."She's been coughing, clearing her throat, a lot of sneezing," Forte said on Monday.Dr. Maxim Lotovsky says it's important to know the symptoms and to get your dog treated as soon as possible."The disease can be fatal if not treated appropriately," Dr. Lotovsky said. "So if your dog seems lethargic, is starting to lose an appetite, and is starting to cough, definitely bring them in. The earlier you get them in, the better a chance we have to rescue your dog."Humans cannot get sick from the dog flu but we can spread the virus. It can live on our hands and clothes for up to 24 hours.It is also easily spread from dog to dog, especially if they share balls or bowls of water."If your dog goes to groomers often, kennels, dog runs and you are mildly suspicious, come in and do a vaccine," Dr. Lotovsky said.Yes, there is an influenza vaccine for dogs, but like the human strain, it is constantly mutating.For Coco, whether it's just a little cough or the canine flu, her owner is not taking any chances.----------