Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that your pup Rocky's nose seems to be dry and is tender to the touch.
Some dogs, the Cocker breed in particular, get proliferative nose leather as they age which is called Idiopathic nasal hyperkeratosis. We can see foot pad thickening as well with this disease process. The nose becomes dry, rough and overproduces skin cells leading to flaking and crusting, especially on the top of the nose. Sometimes we can see cracks and ulcers too, but the color of the nose doesn't change.
Treatment can include the daily topical administration of Kerasolv (made by DVM pharmaceuticals and contains salicylic acid, sodium lactate and urea in propylene glycol), Bag Balm, or tretinoin gel (Retin-A, made by Ortho). Petroleum jelly (Vaseline) can be used as well.
It can help to apply water compresses for 5-10 minutes prior to application of the above products.
Oral vitamin A may also be of benefit. Dosages range from 8,000 to 20,000 Units twice daily.
Nasal Hyperkeratosis Associated with Xeromycteria ("Parasympathetic" nose) is nasal skin proliferation in response to poor oil gland production secondary to the oil glands being damaged by an ear infection. If we resolve the ear infection the inflammation resolves, the oil glands begin working and the nose returns to normal. In the meantime the same treatment that is used for idiopathic nasal hyperkeratosis is used. Does he have an ear infection or has he had one recently?
If his nose is raw and crusty, and has changes in pigment color too then that could be painful and signifies more serious diseases.
A fungal infection (ringworm) or a bacterial infection are other possibilities, especially if he goes outdoors and roots his nose around into things. Diagnosis is by culturing a swab taken from the nose debris and treatment will depend upon culture results.
There are other causes of crusting with erosions and pigment changes of the nose, including solar dermatitis (sunburn), squamous cell carcinoma, or autoimmune skin diseases like Pemphigus or Lupus. Diagnosis is via biopsy.
Treatment can range from topical immunosuppressive drugs (steroids, cyclosporine, or tacrolimus), as well as antibiotics with an anti-inflammatory effect (tetracycline and niacinamide), and sometimes oral immunosuppressive drugs depending upon the response to therapy and how severely the patient is affected.
Ideally because there are so many things that may cause what you are seeing, and while some are relatively benign others can signify more serious disease, it is best your pup see his veterinarian.
For now if his nose is raw I recommend getting in plenty of fluids because he will lose fluids with a raw nose. I recommend adding low salt beef or chicken broths or warm water to canned foods.
I would recommend puncturing a vitamin E capsule and dribbling it on his nose daily to keep his nose leather soft and protected and help with healing.
Best of luck with your fellow, please let me know if you have any further questions