Cornwall, Ontario is not a good place for dogs right now.
Since 2014, the region has seen an usual uptick in cases of canine parvovirus--a virus of the same family that includes human B19 virus, notable for 5ths disease it causes in humans. However, in dogs it can have even deadlier effects, often leading to death, especially in young pups. In this population it can attack the heart.
Canine parvovirus is very persistent and can be spread by direct contact between dogs, but also via surfaces that the animal comes into contact with such as bowls or leashes. When infected, if the dog does not receive supportive care, the mortality rate of the virus can exceed 90%.
While a vaccination against canine parvovirus does exist, most dogs do not get vaccinated until 8 weeks or later, leading to a window of possible infectivity that can be deadly. It also doesn't help that the vaccination is fairly expensive--around $300 for the full series.