Well, if you needed any more encouragement to quit smoking, here's something: second-hand smoke can be just as dangerous for pets as it is for people!
Veterinarian Dr Carolyn MacAllister cites a Colorado State University study that found "a higher incidence of nasal tumors in dogs living in a home with secondhand smoke compared to dogs living in a smoke free environment. The increased incidence was specifically found among the long nosed breed of dogs. Shorter or medium nosed dogs showed higher rates for lung cancer." This difference is due to the fact that carcinogens collect more on long-nosed dogs because there's more surface area; shorter noses lead the smoke more directly to the lungs. The same carcinogens collect on their fur as well, so if they smell like smoke, they're probably getting that nasty stuff internally when they lick or groom themselves!
Even if you don't smoke, be super careful not to let your pup eat cigarette butts she finds on the ground -- they can cause stomach upset or even nicotine toxicity.
So remember: the only kind of butts your pup should be nosing around in are furry ones attached to other animals. Be a quitter -- for dog's sake!