The North American Mastiff

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The North American Mastiff is a newer breed created & curated in the United States. The founders of this breed started strategically picking dogs from different mastiff breeds & lineages around the world. Once known as “Deboar X”, the North American Mastiff began being popularized by Top of the Top Mastiffs & other North American Mastiff Kennels particularly on the West Coast in 2020. The breed still has tons of potential as there are several states in the US that do not have the breed in their area. 

The North American Mastiff Is composed of:

•South African Mastiff (Boerboel) 

•French Mastiff (Dogue de Bordeaux) 

•Italian Mastiff (Cane Corso) 

•Neapolitan Mastiff (Mastino Napoletano)

•Alapaha Blue Blood Bulldog (Not XL, Pitt or other bull breeds)

Top of the Top Mastiffs test ALL of our dogs & our puppy productions for Breed Characteristic, Health Predispositions, & Genetics Traits via Embark. 

🐾 Appearance

• Size: Very large, typically ranging from 130 to 200+ lbs.
• Build: Broad chest, thick bone structure, strong and muscular frame.
• Head: Large, blocky head with a powerful jaw.
• Coat: Short and dense, often coming in shades of brindle, fawn, black, blue, or merle (depending on the bloodlines).
• Ears: Often cropped (depending on the breeder/owner’s choice) but naturally drop-shaped.

🐶 Temperament

• Protective: Bred as a guardian, they’re naturally watchful and loyal to their family.
• Gentle giants: Despite their intimidating size, they’re usually calm, affectionate, and good with kids when well-socialized.
• Confident but not aggressive: They tend to stand their ground, but reputable breeders focus on breeding for stability, not unpredictability.

🏡 Lifestyle & Care

• Exercise: Moderate—daily walks and playtime, but they’re not high-energy like herding breeds.
• Living environment: Do best with space (yard or land), though many adapt to home life if exercised properly.
• Training: Early training and socialization are crucial given their size and power.

Have questions about our breeding program or the puppies we offer? Check out our frequently asked questions page for answers to some of the most common questions we receive. If you still have questions, don't hesitate to contact us.