There are two strains that we know of in dogs. One strain has been in Colorado for a number of years. We do carry vaccinations for this form. There is a new strain of flu that had a major outbreak in Chicago last fall, and has been in the headlines recently. Due to lack of evidence that this strain is here locally, we are not currently carrying the vaccine.
The individual vaccines do not provide protection for both strains. It is recommended that any dog who may be at risk, be vaccinated for both. For dogs who have not been previously vaccinated, they must receive a series of 2 vaccines 3 weeks apart for each strain. Even dogs who have been vaccinated can still become sick, but will hopefully have less severe symptoms and will have those symptoms for a shorter duration.
Flu is easily spread with close dog to dog contact or with contaminated objects. Food bowls, bedding, toys, etc. can be a great line for transmission. Animals being exposed to boarding facilities, dog parks and doggie daycare can have increased risk due to additional chance of exposure.