Many cases are now being traced back to the daycares, The Associated Press reported.

According to The Associated Press, more than 1,100 cases of the canine infectious disease has been reported.

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One veterinarian told WBBM that it is almost an epidemic, the worst outbreak he has seen in his 35 years of practice.

The disease presents as a cough, runny nose and fever WBBM reported, but CBS reported that humans cannot get the illness from their pets despite it being contagious between dogs in close contact with each other.

A simple, $100 vaccine each year is highly effective to prevent the illness.  Treating the flu if a dog contracts it can cost thousands if the animal needs to be hospitalized in isolation, CBS reported.

The illness had been isolated to Chicago, but it has spread to Wisconsin, Ohio and Indiana, Time reported.