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Largest Breed of Dog Recognized by the American Kennel Club

| Updated September 26, 2017

Domestic dogs are a diverse group of creatures, coming in countless colors and shapes. But when it comes to pure size, mastiffs stand out from the rest of the pack. The mastiff breed is the biggest one acknowledged by the American Kennel Club. "Old English mastiff" is an oft-used moniker for this breed. Although mastiffs are the largest dogs, they're not the tallest. That distinction goes to Irish wolfhounds.


Mastiffs are English natives who have extensive histories as watchdogs. Hunting was also a big part of their pasts. Female mastiffs are usually around 27.5 inches at their shoulders. Male mastiffs are generally about 30 inches tall.


Weight is where mastiffs reign. Mastiffs of both sexes usually weigh between 175 and 190 pounds, pretty similar to the range for men. Because mastiffs are so large, they tend to thrive in suburban or rural settings where they can move around. Chihuahuas usually weigh less than 6 pounds, a huge difference within the same species.

Biggest Dogs on Earth

Mastiffs are frequently on lists as the globe's biggest canines. A Massachusetts-based mastiff named Hercules was tagged as the world's heaviest pooch in June 2001. Not only did the immense cutie weigh in at 282 pounds, his neck was 38 inches around.

Tallest Dogs = Irish Wolfhounds

Irish wolfhounds are known as the American Kennel Club's tallest dogs. Males can often grow to at least 32 high at the shoulders. Females can be 30 inches or taller. Males generally weigh 120 pounds or more, while females can weigh 105 pounds or more. Despite their intimidatingly size, Irish wolfhounds tend to have pleasant and friendly dispositions. Because these guys are so tall, ample space in their living environments is a must.