New research has shown that animals exposed to second-hand smoke could develop a host of health problems including cancer, cell damage and weight gain.
The study by scientists at the University of Glasgow found cats were particularly at risk from second-hand smoke, potentially due to extensive self-grooming, and that dogs that had been castrated were more likely to put on weight than those in a smoke-free home.
According to Clare Knottenbelt, professor of small animal medicine and oncology at the university's Small Animal Hospital, the findings of the study showed exposure to smoke in the home was having a direct impact on pets.
"It risks ongoing cell damage, increasing weight gain after castration and has previously been shown to increase the risk of certain cancers, The Telegraph reported.
"We have already shown that dogs can take in significant amounts of smoke when living in a smoking household.
"Our findings show that exposure to smoke in the home is having a direct impact on pets."
The study had also shown that when owners cut the total numbers of tobacco products smoked in the home to less than 10-per day levels of nictotine, cats showed a significantly decline in hair loss, those it was still higher than those in cats from non-smoking homes.
The researchers found that a gene, in the testicles of male dogs which acted as a marker of cell damage, was higher in dogs living in smoking homes than those in non-smoking homes.
The gene had been shown to be altered in some dog cancers in some studies. The effect on the gene was reduced when owners chose to smoke outside the home to reduce their pet's exposure.
Professor Knottenbelt, commenting further on the research, concluded, ''We are all aware of the risks to our health of smoking and it is important we do everything we can to encourage people to stop smoking. As well as the risk to the smoker, there is the danger of second-hand smoke to others. Pet owners often do not think about the impact that smoking could have on their pets.''