

English Mastiffs are at the top of the list. A male can weigh as much as 250 pounds with a height of about 30 inches. The Neapolitan Mastiff gets almost as large, weighing in at as much as 180 when fully grown. While both are mastiffs, their differences are important to note. An English Mastiff is said to be a great family pet, protective, but easy going and good around children. The Neo is very protective, though it rarely barks. A Neo makes a great guard dog.
Saint Bernards are towards the top of the list weighing in between 150 and 250 pounds. This breed is very gentle and tolerant of children. These dogs are known for their strength and as working dogs. Since they are no longer used as Alpine Rescue dogs, they love to spend energy pulling anything. If you own a St. Bernard, consider getting a cart and training him to pull.
Newfoundlands grow to about 30 inches tall and can weigh over 150 pounds and be al long as 6 feet. These dogs are swimmers with webbed paws and love to swim. They have an oily double coat to keep them warm in icy water. The Newfoundland is very gentle with children; known as the "gentle giant". Newfoundlands love to play with other dogs and their humans.
The Irish Wolfhound rounds out this list. They usually weigh between 100 and 125 pounds in adulthood, but are very tall - as tall as 35 inches and as long as 7 feet. This breed is usually friendly to everyone so don't count on it being a watchdog. This breed is good with kids also.
If you are considering adopting one of these breed, it is important to be aware of their needs; dietary, space, health and temperament. A large dog doesn't always need the exercise you may think, but may have special dietary needs.
Big dogs need to be trained especially well. An undisciplined dog and a toddler or elderly person could be a disastrous mix. One jump or bump and someone could easily be injured.
Big dogs have a greater risk of hip disease. Hip dysplasia is a disease that plagues large dogs. Be sensitive to the dogs need to not "sit pretty" or "dance" on command.
Bloat is a condition in which the dog's stomach literally turns itself. This is very common in big dogs. If your pet is one who eats anything and everything, or will eat all food in its bowl at once, be careful of what you leave laying around and how much you feed the dog at each meal. Being aware can help keep bloat from occurring.
Before you adopt any dog, do your research. Is this a breed you can live with? If you are sedentary, you do not want a high energy dog. Information is at your fingertips - just search online the name of the breed you are considering.
I've enjoyed learning a little about these five breeds. I hope this information has helped you too.