Dogs' noses serve as a cooling mechanism since their sweat glands are underdeveloped. The nose stays moist through licking, allowing evaporation to remove heat and keep the temperature lower than other body parts. 

Additionally, a dog's nose has unique patterns, similar to human fingerprints, making it an identification tool. However, it's important to avoid touching a dog's nose since it contains many nerve endings. 

Dogs' noses can also change color due to factors like aging, hormonal changes, inflammation, or nutritional deficiencies. 

A dog's nose can indicate its health and personality traits, with dry or cracked noses signaling potential health issues. 

Dogs with harder noses tend to have stubborn personalities but can still be trained with patience and appropriate guidance.