There have been 12 cases of a highly infectious, very serious canine influenza in Florida. Vets are encouraging all dogs to be vaccinated.

From Dr. Z at All Animal Care in Jupiter:

The canine influenza virus causes a respiratory infection in dogs that is also known as “dog flu”. Common symptoms include sneezing, nasal discharge, and frequent coughing that can last for 2 weeks or more. This is often accompanied by fever, decreased appetite, and lethargy during the first few days of illness. In some dogs this has developed into pneumonia requiring hospitalization. 
CIV can cause respiratory infections in cats as well. In felines, the disease presents as sneezing with nasal discharge and fever, but not usually with cough. 
The virus is spread by direct contact with a sick dog and by contact with an environment or people that are contaminated with the virus, which can last up to 48 hours on a surface. Coughing dogs produce virus-containing mists that travel more than 20 feet in the air, facilitating rapid spread of virus over distances. 
Most dogs do not have immunity to the influenza virus. This means that dogs of any breed, age or health status will likely be infected if they are exposed to the virus. Dogs at most risk for exposure are those with a social lifestyle and participate in group events like boarding facilities, day care centers, rescue shelters, dog parks or the dog beach, especially in communities where the virus is circulating.
Learn more about canine influenza