Generally, studies suggest that dog ownership has an overwhelmingly positive impact on our health. Last year, a headline from a research paper in Sweden called this into question. The study found that people who own a dog with type 2 diabetes are 38% more likely to contract diabetes themselves (1). Cats and their owners were also included in the study, but no relationship was found between feline and human cases. So what’s the link between pet health and human health?

Our pets spend the majority of their lives inside our homes (2). Sharing the same environment means that they are exposed to the same pollutants and chemicals as we are. One example of a shared pollutant is cigarette smoke, this is known to have a damaging effect on the lungs of all species. It is becoming apparent that the health of humans, wildlife, farm animals, companion animals and the environment are often all linked. So, a range of medical, veterinary and environmental professionals are working together to research common factors in the ‘One Health’ movement. The movement aims to ‘promote, improve and defend the health and well-being of all species’. The Swedish diabetes study provides us with a correlation between canine and human diabetes which may give us a deeper understanding and more effective management in both species. 

So what is the environmental factor with diabetes?

Diabetes is an interesting example as no specific environmental cause has been identified. It is possible that pollutants and chemicals in our home affects the production or use of the hormone insulin (3,4). However, diabetes is also more common with obesity, so it is more likely to occur in owners and pets with limited exercise and an energy-rich diet. This may be the common denominator in homes with dogs with type 2 diabetes. 

One study showed that humans and dogs in the same home had a related increase in body weight (5). If we have a tendency to serve large portions of food and walk little, then we are likely to feed our dogs more and walk them less. Therefore, the Swedish study may reflect shared behaviour rather than a chemical or environmental cause. This could be useful as animals can act as sentinels for disease, warning us to change behaviours. If our dog is diagnosed with diabetes, then we may need to look at our lifestyle. Cats are more independent and less affected by our exercise choices, although they may avail themselves of large portions of food. 

The take home message from this study is the diagnosis of diabetes in ourselves or our pets should make us consider our behaviour. ‘One Health’ remains a useful and interesting concept. Anecdotally, it is surprising how often owners suffer with the same condition as their pets. Thyroid disease, cancer and allergy often occur across the species in a household. As more research takes place, we may well discover common environmental influences that contribute to disease. 

What about more direct connections?

Dogs can also affect our health, if they suffer from diseases that we can catch (zoonotic disease). Keeping our dogs healthy is important to protect our family and the population. Common dog parasites can cause disease in humans. For example, both tapeworms and roundworms can cause serious disease in people. Flea bites are mostly an embarrassing inconvenience, but dogs can carry ticks that transmit diseases such as Lyme disease. As dogs travel more than ever before, they can import ticks infected with diseases such as Ehrlichia or Babesia. It is important to control parasites on your dog to protect your own health. 

Leptospirosis is a bacterial zoonotic disease which causes Weil’s disease in humans. This can be fatal and spreads to owners via infected urine. Fortunately, we have an effective vaccine against Leptospirosis to prevent canine infection. Routine preventative health, with extra measures for imported dogs will protect the health of all your household.

So is it all bad?

Not at all – there are huge benefits from pet ownership too! As dog owners we enjoy multiple proven health including a reduction in premature death and heart disease (6), stress reduction, lower rates of depression and increased resilience (7). The increased physical activity of dog walking also results in better health for dog owners compared to cat owners or non-pet owners (8)

Generally, dogs have a positive effect on our health. As more research is undertaken it will be fascinating to assess the environmental factors that affect the health of our pets and us. Managing infectious disease is an efficient way to stay healthy while enjoying our lives with our dogs. When our dog is diagnosed with a disease affected by lifestyle it gives us an opportunity to improve ours.  

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References and further reading

  1. Delicano RA, Hammar U, Egenvall A, Westgarth C, Mubangg M, Byberg L, Fall T and Kennedy B. The shared risk of diabetes between dog and cat owners and their pets: register based cohort study. (2020) BMJ 371 
  2. Day MJ: One health: the small companion animal dimension. Vet Rec. 2010, 167: 847-849. 10.1136/vr.c6492.
  3. Bowe B, Xie Y, Li T, Yan Y, Xian H and Al-Aly Z. The 2016 global and national burden of diabetes mellitus attributable to PM2.5 air pollution. (2018) Lancet Planet Health 2
  4. Ruiz D, jagai JS, Ard K and Sargis RM. Disparities in environmental exposures to endocrine-disrupting chemicals and diabetes risk in vulnerable populations (2018). Diabetes Care 41:193-205  
  5. Nijland ML, Stam F and Seidall JC. Overweight in dogs:but not in cats related to overweight in their owners. (2010) Public Health Nutrition 13 :102-6
  6. Mubanga M, Buberg L, Nowak C, Egenvall A,Magnusson PK. Ingelsson E and Fall T. Dog ownership and the risk of cardiovascular disease and death – a nationwide cohort study. (2017)  Scientific reports 7 :15821 
  7. Johnson RA: Psychosocial and therapeutic aspects of human-animal interaction. Human-Animal Medicine: Clinical Approaches to Zoonoses, Toxicants and Other Shared Health Risks. Edited by: Rabinowitz PM, Conti LA. 2010, Maryland Heights, Saunders Elsevier, 24-36
  8. Christian HE, Westgarth C, Bauman A, Richards EA, Rhodes RE, Evenson KR, Mayer JA and Thorpe RJ. Dog ownership and physical activity :a review of the evidence. (2012) J Phys Act Health. 10(5):750-9