A growing body of evidence continues to point to secondhand smoke as the primary cause of certain kinds of cancers and other health problems in companion animals.
Dogs living with owners who smoke are at particular risk for lung and nasal cancers.
Cats trapped in smoke-filled environments are at risk for malignant lymphoma, a common feline cancer which in under a year takes the life of three out of every four cats that develop the fatal disease.
"The evidence is striking," says Steven Hansen of the ASPCA's Animal Poison Control Center.
"Most veterinarians believe pretty strongly secondhand smoke presents a strong danger to dogs and cats with pre-existing respiratory problems," he says.
"And extrapolating, why would you expose a healthy animal?"