Smoking isn't just bad for human health, it can harm pets, too.

Cats and dogs who are owned by smokers are twice as likely to develop some types of cancer than those pets living in a smoke-free home.

While the danger to humans of passive smoking is well known, many pet owners don't realise the danger to their four-legged friends, according to Val Mills, team leader of Buckinghamshire SmokeFree Support Service.

"As a pet owner I know how important pets can be to people.

"Some people may not realise that smoking around their pets will affect the health of their animals."

Dogs that are exposed to tobacco smoke are much more likely to develop nose and lung cancers than dogs not exposed to smoke.

Smaller pets, like birds, can also be affected as they are very sensitive to the effects of smoke.

Previous research, by Tufts University, near Boston, in the US, also found that cats living with smokers are twice as likely to develop Feline Lymphoma, a serious cancer of the blood and immune system.

Prior to this study, it was thought this type of cancer was caused by a feline leukaemia virus, but the results showed exposure to environmental factors, such as second-hand tobacco smoke, has devastating consequences for cats.

It's believed that when cats groom themselves they ingest contaminated dust, soot, ash and nicotine which was caught in their fur.

Mills also warned that smokers should be aware of the danger of a pet accidentally eating a cigarette.

She claims that this can cause poisoning which, in severe cases, can prove fatal.

However, smoking is not the only way in which pet owner's put their furry friends' lives at risk.

A study by the Association for Pet Obesity Prevention and Mars Incoporated's Banfield Pet Hospital revealed that half of cats and dogs in the US are overweight or obese because they are overfed and not given enough exercise.

As a result, they are more likely to develop cancer, diabetes, arthritis, and kidney failure.

- DAILY MAIL