It’s not an amazing time, but 5 hours, 46 minutes, and 31 seconds is almost certainly now the world record for “Marathon run while carrying a puppy for approximately 75% of the race”.
Update (April 18, 2023): Years later, I stumbled on this post again. The images on the linked article have all gone missing, but I found another article tracking the dog five months later, and it included this fabulous image: