24/05/2026
Why Do Molosser Type Dogs Struggle With Longevity?
This is one of the most interesting and perhaps confronting canine discussions of our time.
Across many of the giant guardian and molosser breeds — Mastiffs, Cane Corsos, Neapolitan Mastiffs, Presa Canarios, St Bernards and others — shorter lifespans seem to consistently appear. It raises an important question:
Why?
Is this simply the biological price of being a giant breed? Is it the result of generations of selective breeding and narrowing genetic diversity? Is modern life itself contributing through processed diets, overfeeding, accelerated growth, reduced working lifestyles and lack of conditioning? Or are we witnessing the consequences of moving further away from functional breeding toward exaggerated appearance?
A fascinating 2024 UK study published in Scientific Reports (Nature Portfolio) attempted to explore some of these questions by analysing over 584,000 dogs across 155 breeds. What makes the study so interesting is not just the scale, but the patterns that emerged.
The researchers found that many of the shortest-lived breeds clustered heavily within the molosser and mastiff families. Breeds such as the Mastiff, Cane Corso, Presa Canario, Neapolitan Mastiff and Caucasian Shepherd all showed significantly reduced median lifespans compared to smaller and more moderate breeds.
One of the clearest findings was the relationship between body size and longevity. Larger dogs consistently showed faster mortality rates than smaller dogs. In simple terms, the bigger and heavier the dog, the earlier biological decline tended to occur.
But size alone did not explain everything.
Another fascinating aspect of the study involved head structure. Researchers compared brachycephalic dogs (short, flat-faced heads), mesocephalic dogs (balanced, proportionate heads), and dolichocephalic dogs (longer, narrower heads).
The mesocephalic dogs — the more balanced and moderate head types — generally showed the best survival outcomes.
That part stood out to me particularly when thinking about the Boerboel.
Historically, the Boerboel has — or at least should have — one of the more balanced heads among the molosser breeds. Powerful and substantial, yet still functional, proportionate and capable. A head that allows breathing efficiency, working ability and athleticism rather than exaggeration for visual effect alone.
The study also found that certain ancestral breed families tended to share similar lifespan patterns. In other words, breeds that are genetically and historically related often displayed similar longevity outcomes. The mastiff and molosser groups repeatedly clustered together among the shorter-lived breeds, suggesting there may be broader biological and genetic factors at play beyond individual breeding programs alone.
What makes this topic especially important today is that it forces us to ask difficult questions about modern breeding direction.
At what point does breeding for visual impact begin interfering with long-term health and functionality?
Can a giant guardian breed remain:
• structurally sound,
• fertile,
• athletic,
• mentally balanced,
• and long-lived?
Or does pushing certain traits too far eventually create biological trade-offs elsewhere?
The study also challenged the simplistic idea that all crossbreeds automatically live longer than purebred dogs. Instead, the researchers suggested the issue is far more complex and may involve:
• genetic bottlenecks,
• excessive inbreeding,
• exaggerated traits,
• loss of functional selection,
• and overall breeding philosophy.
Personally, I think this is where the conversation becomes bigger than just longevity.
It becomes a discussion about purpose.
What exactly are we preserving in our breeds?
Are we preserving functional working animals built for capability, soundness and longevity? Or are we gradually selecting for increasingly exaggerated visual traits that may look impressive but slowly compromise long-term welfare?
The modern Boerboel stands at a very interesting crossroads in that discussion.
Image: Ysterberg Sokket son of Ysterberg Vegter III
