Many diseases and disorders can cause nasal dermatoses in canines. The maladies can include bacterial infections, fungal or parasitic infestations, dietary deficiencies, contact with irritants or cancerous growths. Depending on the cause of the disorders, these may affect the muzzle, just the nose itself, or both. It is also possible for other areas to be affected. In a few of these diseases, only the portion of the nose with hair is involved, while in others, only areas of low pigment are changed. Although any dog breed can develop skin disorders on the nose, certain breeds, such as Collies, are more prone to developing them.

Nasal dermatosis is a broad term that encompasses a number of diseases and disorders that can affect the skin of the canine nose.

There are many diseases and conditions that can affect the skin of the nose in dogs. The symptoms of disease on the nose are varied and can affect both the nose itself or the bridge of the nose. Symptoms you may see could include:

Types 

Some of these disorders are more prone to striking specific breeds. Some of the breed predispositions are:

Bacterial- Bacteria can invade the nasal area through the mucous membranes or through cuts or abrasions to the skin. Some diseases that would be bacterial in nature would be 'superficial bacterial folliculitis' and 'nasal pyoderma'.

Fungal- Common fungal disorders which can attack the nose and face include ringworm and Aspergillus.

Cancer- The most common type of cancer to affect the skin on and around your dog’s nose is a squamous cell carcinoma. Certain breeds, namely the Basset Hound, Collie, Keeshond, and Schnauzer breeds, are slightly predisposed to squamous cell carcinoma, as are dogs with short white coats. Although not the only factor, solar radiation seems to play a large part in developing this disease.

Autoimmune disorders- There are a few autoimmune related disorders that can cause these types of symptoms such as pemphigus foliaceus and systemic lupus erythematosus

Allergies- Allergies can manifest in the skin of the nose in a number of ways. Those with atopic dermatitis are often affected in areas such as the groin, belly and paws too. Sensitivity to plastic can cause your dog’s nose to lighten and a hypersensitive reaction to insect or spider bites are suspected in canine eosinophilic furunculosis of the face.

Dietary- Lack of zinc in the diet or an inability to absorb it effectively can result in zinc-responsive dermatosis, but it is essential to get a diagnosis from your doctor. Supplementing with zinc without veterinary guidance can lead to zinc toxicosis. 

In order to make an accurate diagnosis your veterinarian will ask for a full history of your canine, taking into account anything that may have come in contact with the skin or been inhaled as well as any medications your pet may currently be on. A general physical exam will also be conducted at this time and a complete blood count, biochemistry profile, and urinalysis are likely to be ordered to discover any underlying cause to the symptoms. Samples of any flaking, oozing or crusting skin will be taken for testing. Bacterial and fungal cultures are also indicated in many cases, as well as testing to uncover any underlying dermal allergies that may not have been uncovered by the biochemistry profile. In the case of suspected cancers or autoimmune disorders, biopsies will be ordered to get a final diagnosis.

Treatment of dermal disorders of the nose will be dependent on the underlying cause of the disorder. In bacterial disorders, antibacterial creams, pills or injections may be given. Fungal infections can be treated by removing any lesions, then using antifungal creams and pills, sometimes both together. Steroid treatments  may be prescribed in the case of dermal skin reactions due to allergy or other sensitivity. If itchy, a buster collar can prevent further trauma. In the case of cancer, your veterinarian will want to excise as much cancerous tissue as possible and then treat further with radiation and chemotherapy to try and prevent any new growth. Autoimmune disorders are also treated with immune suppressants including chemotherapy with the aim to reduce the activity in the immune system of the patient. In those cases where nutritional deficiencies are to blame, special diets or supplements will be recommended for your pet by your veterinarian.

While some skin diseases that can affect the nose are not completely understood, there are actions you can take to prevent the likelihood of certain disorders. Using sunscreen formulated for dogs, especially on the nose and face, can help prevent squamous cell carcinoma from developing. Inspecting your dog’s nose and snout regions on a regular basis is a good idea. Ensuring that any cuts or scrapes on your dog’s nose are properly cleaned and dressed will go a long way in protecting from bacteria, fungal infections, and parasites.