Pets in smoking households are at greater risk for weight gain, cell damage and some cancers, according to researchers.
Smoking is the leading cause of preventable disease and death in the US, accounting for around 1 in 5 deaths annually.
According to the Centers for Disease Control and Prevention (CDC), smoking causes around 90% of all lung cancer deaths in men and women, and it is also a risk factor for heart disease, stroke and numerous other illnesses.
But it is not only smokers themselves who are at risk of such conditions; since 1964, around 2.5 million non-smokers in the US have died from exposure to secondhand smoke.
With this in mind, it is perhaps unsurprising that pets living in households where someone smokes are at greater risk for poor health.
Previous research from Clare Knottenbelt, professor of small animal medicine and oncology at the University of Glasgow in the UK, and colleagues has shown that dogs living in a smoking household ingest a high amount of tobacco smoke.
For this latest study - which is ongoing - the team set out to investigate how tobacco smoke exposure impacts the health of cats and dogs.
Cats at greatest risk from smoke exposure
Prof. Knottenbelt and colleagues analyzed the nicotine levels in the animals' fur and looked at whether such levels were associated with any health problems. Additionally, they assessed the testicles of dogs following castration in order to identify any signs of cell damage.
Compared with pets living in non-smoking households, the researchers found that those living in smoking households may be at greater risk of cell damage, some cancers and weight gain.
Cats are most at risk, according to the researchers, because they ingest more smoke than dogs - regardless of whether or not they have access to outdoors. The team speculates that this may be down to the extensive self-grooming cats engage in, causing them to ingest more tobacco toxins.
When analyzing the testicles of castrated dogs from smoking households, the researchers identified a gene that represents a sign of cell damage that is related to some cancers.
Furthermore, they found that dogs that lived in smoking households gained more weight after being neutered than dogs from non-smoking households.
Stopping smoking completely 'best for pets' health and well-being'
However, the researchers also found that these risks reduced when owners smoked outside, therefore reducing the amount of smoke their pets ingested.
While owners who reduced the number of cigarettes they smoked per day did reduce pets' smoke exposure, it was not eliminated completely; cats from households that reduced their cigarette intake to less than 10 daily still had higher nicotine levels in their fur than those from non-smoking households.
The team suggests that pets may even be at greater risk of health problems from smoke exposure than children in smoking households, noting that because pets are lower in height, they are more likely to ingest third-hand smoke - that is, tobacco chemicals present in carpets and other surfaces.
While the research is ongoing, the team believes the results to date should act as a warning to smokers with pets. Prof. Knottenbelt says:
"As well as the risk to the smoker, there is the danger of secondhand smoke to others. Pet owners often do not think about the impact that smoking could have on their pets.
Whilst you can reduce the amount of smoke your pet is exposed to by smoking outdoors and by reducing the number of tobacco products smoked by the members of the household, stopping smoking completely is the best option for your pet's future health and well-being."
So, the next time you get the urge to light up and break that New Year's resolution, just spare a thought for the health of your four-legged friend.
Earlier this month, Medical News Today reported on a study that suggests sharing a bed with your pet could benefit sleep.