1 Certain parts of the brain shrink, especially the prefrontal cortex (an area at the front of the frontal lobe) and the hippocampus. 2  Both areas are important to learning, memory, planning, and other complex mental activities.
Some big, fluffy dog breeds are the chow chow, the samoyed, the standard poodle, the old English sheepdog and the keeshond. The abundant, fluffy coats of these dogs require constant care. Keep Learning.
The 10 Biggest Dog Breeds. 1  Tibetan Mastiff: This handsome dog is known for the lionlike mane around his head. He was bred to guard temples. The biggest Tibetan Mastiff is said to have been around 280 pounds, but these days they average 180 pounds.