Great Pyrenees vs Mastiff — Side by Side

	Great Pyrenees	Mastiff
Lifespan	10-12 years	6-10 years
Size	Giant	Giant
Weight	85-150 lb	120-230 lb
Energy	Moderate	Low
Grooming	Moderate	Low
Shedding	High	Moderate
With kids	Good with kids	With supervision

What actually separates them

Less hair on the sofa with the Mastiff. More with the Great Pyrenees.
Less brushing with the Mastiff. More with the Great Pyrenees.
Calmer of the two is the Mastiff. The one that needs more exercise is the Great Pyrenees.
Great Pyrenees tends to live longer — 10-12 years against 6-10 years.
With young children, Great Pyrenees is the safer default — Mastiff is listed as "With supervision".

The honest downside of each

Great Pyrenees

Bred to guard livestock alone through the night, a Great Pyrenees will bark for hours at anything that moves after dark — that's the working trait doing its job, not a behavior problem, and it makes the breed a poor fit for close neighbors or apartment walls.

Mastiff

A Mastiff's life is short even by giant-breed standards, commonly well under a decade, and that same huge frame carries a serious lifetime risk of sudden, fatal stomach bloat, so you are taking on a very short and potentially very expensive lifespan.

Read the full pages

Great Pyrenees · Mastiff
Health problems, origin and what living with each is actually like.