The number of olfactory cells in dogs can reach 3 million, far exceeding the 5,000 in humans.
Dogs have more than 200 million olfactory cells, and humans have 5 million olfactory cells. The number of dog olfactory cells is 40 times that of humans. The olfactory mucous membrane of a dog can be as high as 30 square centimeters, and the dog's olfactory center is very developed, so dogs are often used as working dogs such as drug detection dogs.
Specially trained dogs can identify cocaine carried by criminals and even the smell of cancer. The owner should pay attention to protecting its sense of smell and not let it smell irritating things.