While it has long been known that small dogs often have longer lifespans than large dogs, researchers in Germany are taking a closer look at why that is.

Their recently published study in the journal American Naturalist concludes that large dogs age faster than smaller dogs and therefore die younger, LiveScience reported.

According to Cornelia Kraus, an evolutionary biologist at the University of Gottingen in Germany, their study of data from more than 56,000 dogs including 74 different breeds showed that dogs lose about one month of life expectancy for each increase of 4.4 pounds (2.2 kg).

"Their lives seem to unwind in fast motion," she told LiveScience.

The disparity in lifespan length is especially evident in two dog breeds mentioned in the LiveScience article: Great Danes and toy poodles. According to the article, a 155-pound Great Dane typically will live up to around seven years, while a 9-pound toy poodle can live up to around 14 years.

Krause indicated that their study will be a jumping-off point for further research to learn which causes of death are most prevalent in large dog breeds. One example that Kraus mentioned is cancer, which she said is believed to cause more deaths among larger dogs.