Dogs and cats have poor eyesight, so they rely on smell to learn the surroundings and communicate with others. The sense of smell is crutial to their survival.
Who do you think have better sense of smell? Dogs or cats?
Dogs have 300 million scent receptors, which is at least 10,000 times more than humans. They can smell as far as 20km, some breeds can even reach 30km. Cats have 100 million less receptors than dogs, so they can only smell within 20km radius. However, it does not mean that cats have worse sense of smell than dogs!
One of the secnt receptors is called V1R, which is responsible for distinguishing odors. Humans have 2 V1R receptors, while dogs have 9, and cats have 30! Although the distance that cats perceive scent is shorter than dogs, they can distinguish similar scent better.
Then why are there police dogs but not cats?
Because cats are born to be masters for you to serve them!