Smoking kills: Cigarette smoke can give your cat cancer

Almost everyone knows that smoking is bad for health. Despite the obvious health risks, millions of people continue to smoke. But smokers not only harm their own health, they hurt the health of those around them: their family, children, and pets. 
With an increasing number of people keeping cats, a large percentage of cat owners are smokers. If you are one of them or living with someone who smokes, you may wonder what effect smoking has on the health of your cat? How can you protect your cat from harm?



Invisible but dangerous: Smoke that poisons your cat after it’s long gone


There is a lot of scientific research showing the dangers of cigarette smoking - and the body of evidence keeps growing. If you smoke you are definitely poisoning your body with many different chemicals that increase your risk for cardiovascular diseases (heart disease), stroke, respiratory diseases, asthma, lung cancer and many other cancers (1, 2). 

What about cats? If you smoke nearby or in the same room as your cat, your cat is forced to breathe toxic chemicals directly coming out of your cigarette, called “secondhand smoke”.

If you think that smoking away from your cat is going to prevent the exposure to harmful effects of tobacco smoke completely, think again. The residue of tobacco smoke still pollutes the air long after the smoke is gone. This is what we call a thirdhand smoke. It is more than just an unpleasant “smoke smell”. The invisible layer of toxic chemicals, like nicotine, stick to your skin, clothing, furniture, carpets, walls, household dust and other things, including your cat’s fur (3). Other harmful compounds go back into the air as gases. They also react with chemicals normally present in the air, like nitrous acid to form new carcinogens, not found in tobacco smoke (4). Your cat breaths in the gases and contaminated house dust. Also when a cat touches surfaces coated with smoke compounds, it accidentally transfers them to its fur. What’s more, these smoke compounds build up inside the house every time you smoke hence they get more toxic with time. 



smoking, cigarette smoke, cat health, thirdhand smoke, secondhand smoke, cancer in cats, Photo credit: Klara Filipenska


How smoking destroys your cat’s health


Unfortunately, there are not many scientific studies investigating the effects of tobacco smoke on cats. 

But we know that cats are exposed to even higher levels of nicotine compared to dogs - they ingest it as a result of grooming themselves (5). 


It is not a mystery that cigarette smoke contains various cancer-causing compounds known as carcinogens. These harmful compounds can potently cause cancer in cats.


Oral squamous cell carcinoma

A cat with oral squamous cell carcinoma located around the teeth. Veterinarians had to remove a part of its lower jaw. A cat survived for a year.


Secondhand and thirdhand smoke have been linked to risk of oral squamous cell carcinoma in cats (6, 7). Oral squamous cell carcinoma is a mouth cancer which often invades bone and is very painful. Cats diagnosed with oral squamous cell carcinoma, even if treatment is given, rarely survive for longer than 1 year.


oral squamous cell carcinoma in cats, cigarette smoke linkA cat with oral squamous cell carcinoma located around the teeth. Veterinarians had to remove a part of its lower jaw. A cat survived for a year. Courtesy: Oncology for veterinary technicians and nurses (2009). John Wiley & Sons.





Thirdhand smoke may be far more damaging for indoor-only cats considering that they are forced to stay inside of the house continuously. Cats exposed to tobacco smoke pollution are at increased risk for lymphoma (8). Lymphoma is cancer that develops in white blood cells (lymphocytes) that are an important part of immune system. Lymphocytes are responsible for fighting off infections.

The symptoms of a cat having a lymphoma are vomiting, diarrhea, anorexia, and weight loss. Even with a proper treatment, like chemotherapy, cats with lymphoma may survive about 2 years.

Secondhand and thirdhand smoke likely cause many more diseases in cats, but without scientific research there nothing can be said with certainty.



e-cigarettes, electronic cigarettes, cat health, smoking



Electronic cigarettes may not safer for your cat


Some e-cigarettes may contain nicotine making them harmful as regular cigarettes.  Even if e-cigarettes come without nicotine you should be concerned about propylene glycol and glycerine, the main components of e-liquids (9). There are other suspicious compounds, but their risks to human and cat health are not well known.  



smoking, cigarette smoke, cat health, thirdhand smoke, secondhand smoke



What should you do?


Give up smoking. If you want to protect the health of your beloved cat, you really need to stop smoking.  Also, the only way to completely protect your cat against thirdhand smoke is to quit. While there are hundreds - if not more - reasons to try give up smoking, there is not a single reason not to. 


Do not smoke inside the home. Smoking in front of an open window or in a different room still exposes your cat to harmful chemicals. It is better to smoke in a balcony with doors closed or go outside. When you come back into the house, the thirdhand smoke comes with you, so wait 10 minutes after smoking to reduce the pollution you bring in (3).


Electronic cigarettes are not harmless. Smoking them around your cat is still risky. 


“Detox” your house. If you stay committed to your decision not to smoke inside the house, it is a good idea to do a major cleaning. Vacuuming won’t be enough. The thirdhand smoke, unfortunately, persists for a very long time, and there is no magical cleaner that could completely remove it.  Replace the carpets, clean up the ventilation system, also wash walls and ceiling of the room you used to smoke in, before covering them with a new coat of paint.


Keep all tobacco products out of reach of cats at all times. Cats generally do not chew on cigarettes, however, there are documented cases of cats ingesting cigarettes or cigarette butts (10), so you never know. Remember, when it comes to your cat you should always think safety first.




Author: P. Aksoy


Cover photo: Nemanja Sekulic



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Click Here To See References

1. Das, S. K. (2003). Harmful health effects of cigarette smoking. Molecular and cellular biochemistry, 253(1-2), 159-165.
2. Sasco, A. J., Secretan, M. B., & Straif, K. (2004). Tobacco smoking and cancer: a brief review of recent epidemiological evidence. Lung cancer, 45, S3-S9.
3. Northrup, T. F., Jacob III, P., Benowitz, N. L., Hoh, E., Quintana, P. J., Hovell, M. F., ... & Stotts, A. L. (2016). Thirdhand smoke: state of the science and a call for policy expansion. Public health reports, 131(2), 233-238.
4. Sleiman, M., Gundel, L. A., Pankow, J. F., Jacob, P., Singer, B. C., & Destaillats, H. (2010). Formation of carcinogens indoors by surface-mediated reactions of nicotine with nitrous acid, leading to potential thirdhand smoke hazards. Proceedings of the National Academy of Sciences, 107(15), 6576-6581.
5. Smith, V. A., McBrearty, A. R., Watson, D. G., Mellor, D. J., Spence, S., & Knottenbelt, C. (2017). Hair nicotine concentration measurement in cats and its relationship to owner‐reported environmental tobacco smoke exposure. Journal of Small Animal Practice, 58(1), 3-9.
6. Bertone, E. R., Snyder, L. A., & Moore, A. S. (2003). Environmental and lifestyle risk factors for oral squamous cell carcinoma in domestic cats. Journal of veterinary internal medicine, 17(4), 557-562.
7. Snyder, L. A., Bertone, E. R., Jakowski, R. M., Dooner, M. S., Jennings-Ritchie, J., & Moore, A. S. (2004). p53 expression and environmental tobacco smoke exposure in feline oral squamous cell carcinoma. Veterinary Pathology, 41(3), 209-214.
8. Bertone, E. R., Snyder, L. A., & Moore, A. S. (2002). Environmental tobacco smoke and risk of malignant lymphoma in pet cats. American journal of epidemiology, 156(3), 268-273.
9. Yang, L., Rudy, S. F., Cheng, J. M., & Durmowicz, E. L. (2014). Electronic cigarettes: incorporating human factors engineering into risk assessments. Tobacco control, 23(suppl 2), ii47-ii53.
10. Novotny, T. E., Hardin, S. N., Hovda, L. R., Novotny, D. J., McLean, M. K., & Khan, S. (2011). Tobacco and cigarette butt consumption in humans and animals. Tobacco Control, 20(Suppl 1), i17-i20.