Cold weather, northern climates linked to more cases of diabetes in dogs

PHILADELPHIA — Cold weather is pretty rough for man’s best friend when it comes to their health. Researchers from the University of Pennsylvania School of Veterinary Medicine reveal that diabetes diagnoses in dogs were most likely to occur in the winter and in the northern United States compared to any other season or region.

This mirrors an association of type 1 diabetes among people in colder weather and climates.

For the study, researchers examined 960 pet dogs with diabetes across the U.S. The team reached out to all of the nation’s veterinary schools, the American Kennel Club, breed clubs, and social media to gain the broadest sample possible. Pet owners filled out a questionnaire that included their dog’s age, the date and age at the time of their diabetes diagnosis, and where they live.

“This link is something that has been discussed in regard to humans with Type 1 diabetes, but it’s never been rigorously looked at in dogs,” says study senior author Rebecka Hess, a professor at Penn Vet, says in a university release. “It’s important to explore because dogs and people live in the same world. If the environment — cold temperatures and seasonality — are important in this disease in both species, it gives us something to look at with further research.”

Study authors knew the date of diabetes diagnosis for 669 dogs in the study. One in three dogs were diagnosed with diabetes in the winter, while 24 percent were diagnosed in the spring and summer, and 19 percent were diagnosed in the fall.

Where do diabetic dogs live?

When analyzing geographic regions, a whopping 46 percent of diabetic dogs lived in the North. That’s compared to 27 percent in the South, 15 percent in the central U.S., and 12 percent out West. Their findings were a bit of a surprise because more than 31 million dogs live in the South, compared to 24 million in the North. About 13 million dogs live in both the central and western regions of America.

“To be honest, I was surprised we found this connection, even though it had been hinted at before. I was always skeptical of the data,” explains Hess. “But when I saw our results, it was quite clear. The findings were strengthened by the fact that diabetes diagnoses were more prevalent in both the winter and the North. Results would have been more difficult to interpret if, for example, we had found increased prevalence in the winter but also in the South.”

Finding a link between vitamin D and the cold

Researchers discovered that three percent of the dogs developed diabetes before their first birthday. These juvenile-onset cases were also more common in colder months and in northern states.

Hess believes diabetes diagnoses are more prevalent in dogs during the winter in the northern region of the U.S. because of how the body processes either vitamin D or insulin. In humans, studies have linked lower levels of vitamin D to an increased likelihood of diabetes, while lower temperatures lead to declines in insulin sensitivity. Researchers don’t believe a dog’s diet contributes to them getting diabetes, since most pet owners use similar dog foods across the country.

Hess wants future studies to examine the vitamin D connection and explore how genetic variability in the vitamin D receptor correlates with diabetes risk.

“Given the close relationship between humans and dogs, and the parallels we see when it comes to diabetes, it behooves us to look,” notes Hess.

The study is published in the journal PLOS ONE.

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