Your dog is a......

American Bulldog

QUICK FACTS:
Origin: United States
Life Span: 10-15 Years
Litter size: 7-16 puppies
Weight: Males: 34–52 pounds / Females: 27–41 pounds
Height: Males: 50-65cm/20-26in / Females: 51-61cm/20-24in
Fur: Short but harsh
Color: All white or white with patches of red or varying degrees of brown, brindle, or fawn.

Source: Wikipedia