Just as with people, secondhand smoke can prove harmful to your dog. Certain dogs, including long-nosed dogs, have an increased risk of acquiring health problems from exposure to secondhand smoke. Not every dog exposed to secondhand smoke will develop health problems, but it is clear that they do have an increased chance of developing cancer, asthma, lung infections, respiratory problems, and other conditions. The best approach is a preventative one, thus limit your dog's exposure to secondhand smoke.