The title of "heaviest dog breed" is a little tricky, as it depends on how you define "heaviest."
If you are looking for the breed with the highest average weight:
English Mastiff: This giant breed typically weighs between 160-230 pounds, making it the heaviest breed on average.
However, if you are considering the heaviest individual dog ever recorded:
The record goes to an English Mastiff named Zorba, who weighed a staggering 343 pounds!
So, while the English Mastiff is considered the heaviest breed overall, individual dogs of other breeds can sometimes surpass them in weight.