VetCompass Australia examined clinical records of 3,085 intact and 4,100 neutered Rottweilers.
Males neutered before one year of age lived one-and-a-half years and females one year shorter than their intact counterparts.
Neutered dogs under four-and-a-half years had similar results.
"Our study was one of the first to show that neutering dogs does not increase their lifespan," said study lead author and JCU Senior Lecturer in Veterinary Reproduction Dr. Carolynne Joone.
That wasn't what we found, which was surprising. We had statistics on when dogs were desexed and died, which was lucky."
Even so, Dr. Joone advised owners to neuter their dogs and manage their weight gain, which was frequent after the treatment.
Screening for genetic problems and choosing healthy breeding couples may reduce Rottweiler inherited health issues and increase longevity.