Most dogs can understand up to 250 words and phrases making them as intelligent as the average 2-year-old child. Puppies have 28 teeth and adult dogs have 42.
Until recently, scientists thought dogs drank water by forming their tongues into a little cup. However, it has been discovered that they can drink water because the water sticks to the tongue and is pulled into their mouths in a column.
Spiked collars, such as the prong collar used for training, were invented in ancient Greece. Their original purpose was to protect a dog's throat from wolf attacks. In ancient Rome, mastiffs were fitted with armor and sent to fight alongside mounted knights.
Although dogs are popular pets throughout the world, the United States has the highest dog population of any country. Presidents such as Lyndon Johnson, Barack Obama and Franklin D. Roosevelt all had dogs in the White House.
If a dog is not spayed or neutered, his family, along with his mate and puppies are capable of producing 66,000 dogs in 6 years. For the first few weeks of life, puppies sleep 90 percent of the day. There are around 5,000 puppies born in the United States each year. It takes most puppies 12 days to open their eyes after their born.