The health benefits of owning pets have been well-documented. However, a research team in Georgia Southern University’s Jiann-Ping Hsu College of Public Health (JPHCOPH) led by professor and medical epidemiologist, Jian Zhang, M.D., DrPH, has been exploring the other side of pet ownership to answer the question — could furry companions actually be harmful to your health?
In the United States, 68% of U.S. households, or approximately 85 million families, own a pet, according to the 2017-2018 National Pet Owners Survey. More than 60 million homes have a dog, while more than 47 million households and 7 million have cats and birds, respectively.
“Any detrimental impact of pet ownership, even too small to be detected statistically, if overlooked, can be translated into a substantial health impact at population level,” said Zhang.
To explore the potential risks of pet ownership, the research team analyzed large data sets from the third National Health and Nutrition Examination Survey conducted almost 30 years ago. The team, which includes JPHCOPH master’s and doctoral students, and faculty investigators community health educator, Andrew R. Hansen, DrPH, and environmental health scientist, Atin Adhikari, Ph.D., was able to link more than 17,000 survey participants with a national data bank of death certificates to ascertain whether each survey participant remained alive. If not, what cause(s) of death were listed on the death certificate? These unique longitudinal data sets of nationally representative samples offered the JPHCOPH team a 360-degree view on the relationship between pet ownership and health effects, both beneficial and potentially harmful.
Research on human-animal interactions remains inconclusive. Some previous studies have shown positive health effects, but the results have been mixed. According to the Centers for Disease and Prevention, heart disease is the leading cause of death in the United States, claiming more than 640,000 lives each year. It’s well-documented that companion animals improve the survivability of cardiovascular patients, but it remains unclear whether pets are also good in prevention of cardiovascular mortality among populations without well-documented cardiovascular risk factors.
The first study from the research team looked at the relationship between pet ownership and the risk of dying from cardiovascular diseases among generally healthy adults and found that owning a cat significantly reduced the hazard of dying from stroke, especially in women. Owning a dog didn’t seem to impact the cardiovascular outcome at all.
Cancer is the second leading killer in this country, causing more than half a million deaths annually. The second study from the pet research group examined the relationship between pet ownership and cancer. Women, not men, were found to be more likely to die from cancer if they kept a pet at home. Further breaking down the data, research found that it was birds and cats that put women at an elevated risk of dying from cancer compared to those who had neither birds nor cats. Women who owned birds were 2.41 times more likely to die of cancer and those who owned cats were 1.48 times more likely.
Lung cancer causes the most deaths in this country, killing 154,000 Americans in 2018. The third study specifically examined the risk of dying by pet owners from lung cancer. The findings confirmed with more confidence that women were vulnerable to the cancer risk associated with birds or cats. Women who owned birds or cats more than doubled their risk of dying from lung cancer compared to their counterparts who did not keep a cat or a bird in the home. Interestingly, the risk was not significant at all for dog owners or for male pet owners of any type of pet. The detrimental effects from pets was not explained by cigarette smoking or other conditions.
The researchers continued their efforts by assessing the relationship between pet ownership and colorectal cancer, the second leading cancer killer in this country. The fourth study found that, again, a cat was significantly associated with an elevated risk of dying from colorectal cancer, especially in women. The observed detrimental effects the cats conferred were not explained by confounding effects from sociodemographics, cigarette smoking, sedentary life or atopic conditions. No association was found with having a dog. The evidence consistently points to cats and birds and women were observed to be more vulnerable for both lung cancer and colorectal cancer independently, making the researchers believe that the chance played a limited role in this series of studies.
Georgia Southern students and faculty make continuous efforts to look at links between pet ownership and a number of other health conditions in order to explore public health strategies and clinical practices that maximize the benefits of pet ownership and minimize the potential detrimental impacts.
“This research effort also presents great opportunities for graduate students to get hands-on research experience and build their research identity,” stated Zhang.
Information from Georgia Southern.