The H3N2 strain of canine influenza that spread across the Midwest last year sparked panic among dog owners and prompted both Merck ($MRK) and Zoetis ($ZTS) to speed vaccines to the market to prevent the emerging virus. Now there's growing concern that this strain of dog flu can spread to cats. The Wisconsin School of Veterinary Medicine has confirmed that multiple cats at a shelter in Indiana tested positive for H3N2 after exhibiting respiratory symptoms. Veterinarians there believe the virus is also capable of replicating and spreading from cat to cat. So far there have been no fatalities, and the affected animals have been quarantined. There is no flu vaccine on the market for cats. Article