Modern science is finally catching up to what dog lovers have known for thousands of years — that dogs are good for people.
From understanding disease to helping us live healthier lives, the following are a few examples of how dogs benefit people.
Since dogs share our environment, they are exposed to similar water, air and potential toxins. And many human diseases have similar counterparts in dogs. With their shorter lifespan compared to humans, studying disease in dogs can sometimes be done faster with larger numbers and fewer ethical dilemmas.
Purebred dogs are especially useful for studying rare genetic diseases. Using non-invasive samples, such as blood and cheek swabs, purebred dogs with a disease that is also seen in humans can be used to identify abnormal genes.
Pedigree records can also provide clues about modes of genetic disease inheritance. Studies of this sort require far fewer cases than equivalent humans studies. Once defective genes have been discovered in dogs, they can be subsequently confirmed in human cases of the same disease.
A success story involving this type of comparative medicine involves ichthyosis (“ik-thy-os-is”), a congenital skin disease that affects both people and Golden Retrievers. In affected people and dogs, the outermost skin layers do not mature properly. The skin doesn’t shed normally, leaving a thick layer of dry, scaly skin that is prone to secondary infections with bacteria and yeast.
French researchers used samples from 40 Golden Retrievers (20 with ichthyosis and 20 normal dogs) to find genetic changes associated with the disease in a study published in 2012 in Nature. They identified a mutation in a gene called the PNPLA1.
Using this information, they analyzed DNA samples from people with the same disease, discovering that the human patients had the same genetic defect. Without the help of dogs, researching the disease in humans would have been like looking for a needle in a haystack because the disease is so rare, and it would have taken a very large group of people to identify the gene.
Assembling a sizable group of people with a rare genetic disease and garnering their co-operation is a continual challenge to genetic researchers.
In addition to those warm-fuzzies you get when your dog greets you, dogs may hold the key to healthier hearts and cardiovascular systems. Many studies have shown that dog owners have lower blood pressure. In one of these studies, people with high blood pressure were allocated to two groups. The first was instructed to immediately adopt a dog while the second was asked to wait to adopt a dog. They found that the group that became dog owners right away had significantly lower blood pressure compared to the group that waited. When the second group acquired dogs, they achieved similar blood pressure reductions as the first group.
With regards to lowering cholesterol, dog ownership seems to have mixed results: some studies show a benefit while other studies that consider physical activity levels, age and body mass index did not find a positive benefit. However, there is evidence to suggest that dog owners that suffer heart attacks are much more likely to survive compared to non-dog owners.
Many studies in North America have documented the consistent association between dog ownership and increased activity. For example, a Canadian study found that dog owners walked nearly twice as many hours per week compared to non-dog owners. Along a similar thread to the blood pressure study, people who acquire dogs become significantly more active than before they had a dog.
In terms of weight loss, dogs are ideal exercise companions, providing owners with both motivation and positive reinforcement. Those who consistently walk their dogs tend to have lower body mass indexes. As well, families with dogs experience lower rates of obesity among their children.
As the evidence grows for positive benefits to human-dog interactions, the future may bring a time when family physicians prescribe dog ownership as treatment for high blood pressure, heart attacks and obesity.
(Look for the second part of this column next month.)
Dr. Jamie Rothenburger, DVM, MVetSc, PhD, DACVP, is a veterinarian who practices pathology and is an assistant professor at the University of Calgary’s Faculty of Veterinary Medicine.