My dog is six years old and has an extremely hard, dry, crusty nose. Parts of it even flake off. It used to be shiny and moist. What causes this and is it serious?

There are several possible causes.

There are numerous causes for a dry, crusty nose. This is definitely a problem that a veterinarian or veterinary dermatologist should address for you. Some potential causes include endocrine or hormonal disorders, disorders of the immune system, infectious agents, inflammatory diseases, underlying metabolic disorders, and cancer. Some older dogs just get a dry nose as part of the aging process. The history of the problem, physical exam findings, and diagnostic tests are all used in diagnosing and treating the problem. As far as diagnostics, a blood chemistry panel and urinalysis are excellent screening tests to narrow the range of possible problems. Conducting more specific blood tests can eliminate most of the remaining diagnostic possibilities. Additionally, a skin scraping, impression smear, and skin biopsy are procedures that may be needed to make definitive diagnosis. Your veterinarian may be able to do all of these procedures or may wish to refer you to a veterinarian who specializes in dermatologic disorders. Good luck in your endeavors.