Not long ago I saw a very friendly Collie whose owners were concerned about his nose. It was drier than they thought it should be. Did this mean he was sick?

I evaluated my patient. He was very bright and alert and happy. He was normally engaged with his environment, and he showed no signs of sensory or neurological dysfunction. He tolerated a thorough oral exam, which was unremarkable (that’s doctor-speak for “normal”). The tips of his nostrils were slightly crusty and his nose was not as moist as an average dog’s would be. His heart, lungs, abdomen, pulses, and lymph nodes were all unremarkable. The exam was, overall, not very impressive (that’s a good thing — you rarely want your doctor to be impressed).

Some discussion ensued. During it, I learned that the dog had not been coughing or sneezing. He had not been lethargic or inappetant. His nose did not seem painful, it had not been bleeding, and he had not been licking it excessively. His behavior had been normal in every way. There was only one problem: His nose was slightly crusty and not wet and cold.

So was he sick? The answer is complicated in this case, but it boils down to no.

There is a loose — loose — correlation between a cold, wet nose and health in dogs. The average dog has a nose that is cool and moist. In some cases it will be moist in the extreme — my pal Buster is not allowed on the sofa due to his propensity to deposit a pool of watery nasal secretions during naps.

But some dogs aren’t average. They naturally have warm, dry noses, and that doesn’t mean they’re sick. Some dogs’ noses simply don’t produce as much watery discharge as other dogs’ noses.

The key to knowing whether something might be wrong with your dog is to monitor trends that occur with his nose. A dog whose nose is normally cold and wet may exhibit a warm, dry nose if he has a fever or is dehydrated.

But, emphatically, a dry nose is not a good proxy for fever. This urban legend has been around for much longer than I have, and although there is a small kernel of truth in it, overall it doesn’t apply well. The only way to know whether a dog truly has a fever is to take his temperature.

And be aware that even a change in the temperature and moisture levels of your dog’s nose does not necessarily indicate something is wrong. Some dogs’ nasal secretions vary over time; they may cycle throughout the day or week, or they may change over the course of a dog’s life.

Long story short: Although a cool, moist nose is normal, a warm, dry one isn’t necessarily abnormal either. If your dog’s nose seems warm and dry and he isn’t exhibiting discomfort, sneezing, licking of the nose, lethargy, poor appetite, or any other symptoms, then it’s unlikely that anything is wrong. However, a trip to the vet is always the best option if you have any concerns whatsoever — and although in the case of a warm nose such a trip is likely to put your mind at ease, it’s always better to be safe than sorry.

In the matter of the Collie in question, although he did not have evidence of a significant problem, he may have been in the early stages of a mild autoimmune disorder. It was not the warmth or dryness of the nose that was the cause for concern; rather, it was the crusting. There are several syndromes with scary names, such as discoid lupus erythematosus and pemphigus foliaceus, that can cause the mucosa (hairless portion) of the nose to change consistency. Crusting, scabbing, blistering, or loss of pigment can occur. Solar dorsal nasal dermatitis — essentially a form of sunburn — can cause changes to the mucosa of the nose as well. Exposure to the sun can also exacerbate autoimmune disorders.

These autoimmune disorders often manifest with mild symptoms, which are limited to the nose and do not require significant intervention. However, it is possible for more severe generalized skin or autoimmune disorders to occur; in some instances, significant changes to the texture of the nasal mucosa can be harbingers of more serious problems in the future. Affected dogs may exhibit significant nasal scabbing, crusty discharge on the mucosa of the nose, and pain (as manifested by sensitivity or excessive licking of the nose) before the conditions progress to more serious generalized autoimmune disorders.

Therefore, if your dog’s nose exhibits a change in color or consistency, I recommend an immediate veterinary checkup. Your vet may recommend a biopsy to determine the nature of the issue, as well as to determine what (if any) treatments are necessary.

Learn more about dogs with Dogster:

• 9 Tips for Keeping Your Dog Cool This Summer
• Let’s Talk: Does Your Dog Love to Roll in Stinky Things?
• Be Polite to Your Dog — It Benefits Both of You

Got a question for Dr. Barchas? Ask our vet in the comments below and you might be featured in an upcoming column. (Note that if you have an emergency situation, please see your own vet immediately!)