A new study published today takes an in-depth look at how a dog’s size affects its health. The study found evidence that larger dogs tend to be at higher risk for many health problems and often live shorter lives, while also suggesting that smaller dog breeds also have their own unique health risks.
The research is the latest Dog Aging Project, an initiative hailed as the most ambitious of its kind in the world. The project aims to track companion dogs over a 10-year period to better understand the factors that help dogs and humans live longer, healthier lives. Volunteer pet owners are asked to fill out annual questionnaires about their dogs’ health, and some will also provide veterinary records and test samples for use in small studies.
For this study, publish On Wednesday in PLOS-One, researchers looked specifically at dog size, looking for potential links between body size and a host of health conditions. Ultimately, they looked at data from more than 27,000 dogs across 238 breeds.
Overall, they found that larger dogs were more likely than smaller dogs to suffer from a number of different diagnosed health problems. These problems include cancer, ear, nose and throat diseases, neurological disorders and gastrointestinal problems. However, smaller dogs are more likely to develop eye, heart, and liver problems, as well as respiratory problems. The risk of kidney and urinary tract problems appears to be the same for both large and small dogs. These patterns persisted even when the researchers tried to account for factors such as gender, where the dogs lived and whether they were purebreds or mixed breeds. But both age and size appear to affect a dog’s risk of developing many health problems throughout his or her lifetime.
Such studies cannot directly prove a cause-and-effect relationship between a dog’s size and health—they can only establish a correlation. But researchers say the findings, combined with other evidence, do strengthen the idea that large dogs do live shorter lives than small dogs. The findings revealed in the new paper may also spark some new areas of interest for future research.
For example, contrary to some past studies, the authors found that larger dogs were more likely to develop hormone-related problems, particularly hypothyroidism (an underactive thyroid gland that leads to weight gain, lethargy, skin problems, and more). The authors note that if this increased risk is real, greater awareness of it could go a long way toward helping large dogs stay healthy, especially since hypothyroidism is relatively easy and inexpensive to treat.
“These results provide insights into the categories of diseases that may contribute to shortened lifespan in large dogs and suggest multiple avenues for further exploration,” the researchers wrote.
The Dog Aging Project is still ongoing, and the lessons we learn from it will only help scientists and dog owners find the best ways to keep dogs healthy and live long, productive lives.
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