What is that on my dog's nose?

I have an 8year old female American Pit Bull Terrier and since she was about 2years old she developed this brown dirt-like crust on her nose. I read this is common in kennel cough and puppies but she has never had kennel cough. I've tried to wipe her nose and she pulls away from me or hides her face. What is the cause of this? Is it harmful to her? What can I do to fix it? Please be as detailed as possible.

This could be due to allergies, sunburn, bacterial infection or something worse like hormonal imbalance, metabolic disorders and even cancer. Its not very harmful if it comes from the first three causes but can be painful as any chapped skin. The first thing you should do is make sure her dishes are always cleaned, especially plastic bowls that harbor bacteria. Limit time outside in the sun, cold, or dry weather. They do make nose butters for dogs' noses. Vasoline may help too. If nothing helps over a good amount of time I recommend a veterinary dermatologist.

As detailed and as simple as I can make it: If you, the writer of this question, believe or think or suspect that your pet, your dog, has an illness or injury, then you should take your doggy to the doggy doctor, who is also a veterinarian..