A dog's lifespan can be affected by a variety of factors, including breed, genetics, diet, exercise, and healthcare. Larger breeds tend to have shorter lifespans than smaller breeds, with some giant breeds only living to be around 6-8 years old. Genetics also play a role, with certain breeds being prone to specific health issues that can shorten their lifespan. A healthy diet and regular exercise can help extend a dog's lifespan, as can preventative healthcare such as vaccinations and regular check-ups with a veterinarian. Overall, providing a dog with a healthy and happy lifestyle can help ensure a longer and more fulfilling life.