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Dog Coughing Up Snot (Why It Happens)

By Patricia Williams
Last updated: November 17, 2025

A dog coughing up snot can be alarming, especially when you suddenly see mucus come out during or after a coughing fit.

While it can sometimes be caused by mild irritation or allergies, coughing up visible mucus often means something deeper is happening in the respiratory system.

We outline the common reasons why a dog may cough up snot, what you can do at home, and when to seek veterinary help.

Table of Contents

Dog Coughing Up Snot: Why It Happens

A dog may cough up snot when mucus builds up in the respiratory tract and the body tries to expel it through coughing.

This can happen with infections, nasal inflammation, allergies, throat irritation, or deeper conditions affecting the lungs. As mucus travels from the nose or upper airway into the throat, coughing becomes the body’s way of clearing it.

Dogs with more severe respiratory issues may also cough up thicker or unusually colored mucus, especially during infections or inflammatory conditions.

Dog Coughing Up Snot: Common Causes

Upper Respiratory Infections

Upper respiratory infections—whether viral, bacterial, or a combination—are the most common reason dogs cough up snot.

When the nasal passages and throat become inflamed, mucus production increases significantly.

As mucus drains down the back of the throat, your dog may cough forcefully enough to bring it back up. You might notice sneezing, congestion, noisy breathing, or thick nasal discharge along with the cough.

Because the tissues are irritated, even a mild cough can cause mucus to be expelled. The snot may be clear in early infections but can turn cloudy or yellowish as inflammation progresses.

These infections are often contagious, especially in environments like parks, daycares, or kennels.

Kennel Cough

Kennel cough affects the trachea and upper airway, making the throat extremely sensitive. When the dog coughs, the force can push up mucus that has collected in the throat or nasal passages, resulting in snot being brought up.

The classic kennel cough sound is a loud, dry, hacking cough, but as the condition progresses, dogs may gag, retch, or expel clear or yellowish mucus.

The irritation in the airway makes coughing almost constant, especially when your dog gets excited or pulls against a collar.

Because mucus production increases with airway inflammation, coughing up snot can be a normal part of the illness. However, thick or discolored mucus can also signal a secondary infection that requires treatment.

Allergies

Dogs with allergies often develop excess mucus in the nose and throat due to the inflammation caused by allergens like pollen, dust, mold, grass, or household scents.

This mucus can drain backward, triggering coughing fits. Dogs with allergies may cough up clear snot, especially during high-allergen seasons or when exposed to irritants like smoke or strong cleaning products.

You may also see sneezing, watery eyes, paw licking, and itchy skin. Because allergic inflammation makes airway tissues sensitive, coughing up snot can happen even without a respiratory infection.

Dogs living in dry or dusty homes, or those exposed to perfumes or aerosols, can develop irritation that leads to mucus buildup as well.

Nasal Infection or Sinus Issues

A localized infection in the nasal passages or sinuses can produce thick mucus that drains into the throat. When enough mucus accumulates, the body uses coughing to clear it out—resulting in snot being coughed up.

These dogs often have chronic nasal discharge, noisy breathing, or difficulty smelling. You may notice your dog snorting or pawing at the nose, especially if pressure builds in the sinuses.

Because sinus infections can linger for weeks or months, coughing up snot can become a long-term issue if left untreated.

Lower Respiratory Disease

When infection or inflammation reaches deeper into the lungs, mucus production increases dramatically. This mucus must travel up the airway to be expelled, leading to coughing up snot or thicker phlegm.

Dogs with pneumonia may have wet, congested coughs that produce mucus, rather than the dry cough seen with kennel cough.

They often show other serious symptoms, including lethargy, fever, difficulty breathing, or loss of appetite. The snot or mucus may appear yellow, green, or cloudy due to infection.

This is one of the more serious reasons a dog may cough up mucus and always requires veterinary attention.

Nasal Blockage

Dogs that sniff grass, dirt, or debris can inhale small particles or foreign objects such as seeds or plant material.

When something lodges in the nasal passages, the body produces mucus in an attempt to flush it out.

This mucus may eventually get coughed up, or the dog may sneeze it out. Repeated coughing, gagging, or sudden onset nasal discharge—especially from one nostril—may indicate a foreign object.

In more severe cases, an object may partially obstruct airflow, leading to persistent mucus buildup and coughing.

What to Do If Your Dog Is Coughing Up Snot

Start by giving your dog a calm, comfortable space and observe the frequency and severity of the coughing episodes. Keeping your dog hydrated can help thin mucus, making it easier to expel without excessive coughing.

Try running a humidifier in the room where your dog rests. Moist air helps soothe irritated nasal passages and loosens congestion, easing coughing fits.

Avoid exposing your dog to smoke, strong fragrances, dust, or cleaning sprays. Even mild irritants can worsen mucus production and intensify coughing.

If your dog normally pulls on the leash, switch to a harness to minimize pressure on the throat. Reducing throat irritation can decrease the amount of mucus your dog coughs up.

Offer warm, easy-to-eat meals if your dog seems congested or less eager to eat. Soft food can be gentler on inflamed tissues and can encourage eating, especially when your dog is under the weather.

Monitor your dog closely for any changes in mucus color, energy level, breathing, or appetite. Mild cases of nasal irritation or early allergies may improve at home, but persistent coughing up snot always deserves medical attention.

When to Call or Visit Your Vet

You should contact your veterinarian if your dog coughs up snot multiple times a day, or if the coughing continues for more than a few days.

Thick, yellow, green, bloody, or foul-smelling mucus is a key warning sign of infection and needs prompt evaluation. Breathing difficulty, lethargy, fever, or loss of appetite indicate the possibility of pneumonia or a severe respiratory problem.

If your dog coughs after excitement, seems to gag or choke during coughing fits, or brings up large amounts of mucus, this may suggest kennel cough, tracheal irritation, or deeper airway involvement.

One-sided nasal discharge, sudden snorting, or pawing at the nose could indicate a foreign object, which requires urgent veterinary care to prevent complications.

Puppies, senior dogs, and brachycephalic breeds should always be seen sooner, as they are more vulnerable to respiratory distress.

Key Takeaway

A dog coughing up snot often means there is mucus buildup in the respiratory system, typically caused by infections, allergies, throat irritation, or deeper lung problems.

While mild cases may resolve with rest, hydration, and reduced irritant exposure, persistent mucus production requires a veterinary exam to determine the underlying cause.

With close monitoring and timely care, most dogs recover well and breathe comfortably again.