Why Is My Dog’s Nose Running? 6 Causes to Watch For

My dog is my work-from-home office buddy, so when I noticed his nose running today, I was surprised.

I knew a moist nose was normal, but I’d never seen one of my dogs with a runny nose before. A healthy canine nose is typically cool and slightly damp, which helps them absorb scent chemicals, but active dripping is a different matter entirely.

Can dogs catch colds? As it turns out, they can develop respiratory infections similar to human colds, although different viruses are usually responsible. Dogs cannot catch the human rhinovirus, but they are susceptible to their own set of pathogens, including canine parainfluenza and adenovirus.

Here are six common reasons your dog might have a runny nose.

1. Respiratory Infections

Dogs can develop upper respiratory infections caused by viruses or bacteria, including those associated with kennel cough. Highly contagious, kennel cough—often linked to the bacterium Bordetella bronchiseptica—spreads rapidly in places where dogs gather, such as boarding facilities, dog parks, and grooming salons.

Along with a runny nose, symptoms may include sneezing, coughing, congestion, watery eyes, tiredness, and a reduced appetite.

2. Allergies

Just like humans, dogs can react to pollen, dust, mold, and other environmental allergens. Canine atopic dermatitis, a chronic condition triggered by inhaled or absorbed allergens, affects an estimated 10% to 15% of the dog population.

Allergies may cause clear, watery nasal discharge, sneezing, and watery eyes.

You might also notice your dog scratching, licking their paws, or experiencing itchy skin.

Image: ElleVet Sciences

3. Something Stuck in Their Nose

Curious dogs sometimes inhale grass seeds, dirt, or other small objects while sniffing outdoors. Foxtails, a type of barbed weed seed common in the western United States, are particularly notorious for migrating into canine nasal passages and causing severe irritation.

If something becomes lodged in a nasal passage, your dog may suddenly start sneezing repeatedly or pawing at their nose.

Discharge from only one nostril can be another warning sign.

4. Environmental Irritants

Household products and strong smells can irritate a dog’s sensitive nose. Because a dog’s olfactory system contains up to 300 million receptors compared to a human’s roughly 6 million, everyday scents can be overwhelmingly harsh.

Cigarette smoke, perfumes, air fresheners, and cleaning sprays may trigger temporary sneezing or watery discharge.

Image: Walkerville Vet

5. Dental Problems

Surprisingly, a runny nose can sometimes be connected to dental health. The roots of a dog’s upper premolars and molars sit directly beneath the nasal cavity floor, separated by only a thin layer of bone.

An infected upper tooth may affect the nearby nasal cavity, resulting in discharge from one nostril.

Other clues include bad breath, difficulty chewing, or discomfort around the mouth.

6. Nasal Growths or Other Conditions

Persistent nasal discharge can occasionally indicate a more serious condition, such as a fungal infection, nasal polyp, or tumor. Fungal infections, particularly those caused by Aspergillus, are more frequently diagnosed in long-nosed breeds like Collies and Greyhounds.

These problems may be particularly concerning in older dogs.

Bloody mucus, noisy breathing, or discharge from only one nostril should always be checked by a veterinarian.

What Does the Color of Your Dog’s Nasal Discharge Mean?

The appearance of your dog’s nasal discharge may provide clues about what’s happening.

Clear and watery: Often normal, but can also indicate allergies, mild irritation, or an early infection.

White or cloudy: May suggest inflammation or an infection.

Yellow or green: Can indicate inflammation or a possible bacterial infection.

Pink, red, or bloody: May result from an injury, foreign object, infection, or nasal disease.

Keep in mind that mucus color alone cannot determine the cause of your dog’s symptoms.

When Should You Worry About a Runny Nose?

If your dog is eating, playing, and behaving normally, a small amount of clear discharge may simply need monitoring.

However, contact your veterinarian if the discharge continues, becomes thick or discolored, comes from only one nostril, or appears alongside coughing, tiredness, or a loss of appetite.

If your dog is struggling to breathe, seek emergency veterinary care immediately.

How Can You Help a Dog With a Runny Nose?

For mild symptoms, make sure your dog has plenty of fresh water and a comfortable place to rest.

Avoid exposing your dog to smoke, perfumes, and strong cleaning products. A plain humidifier may also help ease mild nasal congestion.

Never give your dog human cold or flu medications unless specifically instructed by your veterinarian, as some ingredients—such as acetaminophen and pseudoephedrine—can be highly toxic to pets.

Final Thoughts

A runny nose isn’t always a reason to panic, especially if your dog seems happy and healthy otherwise.

The important thing is to pay attention to changes in their normal behavior and recognize when something doesn’t seem right.

Knowing the difference between occasional moisture and persistent or unusual discharge can help you decide when it’s time to call your veterinarian.