The largest-ever study of dog behavior, tracking more than 47,000 pets, reveals how breed, size, sex, and age shape canine traits. In addition to breed-specific traits, dog behavior is, broadly speaking, inextricably linked to well-being. A new large-scale study jointly led by researchers from Virginia Tech and the University of Washington has established a crucial baseline for understanding the link between dog behavior and health. Nonetheless, the huge study gives scientists a starting point to track how dog behavior changes over time, especially as dogs age. Further studies are needed to explore how factors such as a dog’s location or their health status influence behavior over time.