Why does my dog have a runny nose?

A runny nose in a dog is one of those things that makes owners worry — and rightly so. A wet or dripping nose can be harmless, an annoyance, or the first sign of something that needs prompt veterinary care. Understanding the likely causes, the biology behind nasal discharge, and the practical steps you can take at home helps you decide when to relax and when to call for help.

What a runny nose tells you about your dog’s health and comfort

When a dog’s nose is running, owners are often juggling three concerns: the dog’s comfort, the risk of contagion to other pets, and the potential cost of diagnosis and treatment. I typically see owners who are most anxious when the discharge is thick, bloody, smells bad, or is clearly making the dog miserable. Small puppies and elderly dogs raise a different level of concern because their immune response may be weaker.

Common situations that prompt a call include a puppy with clear watery sniffles after daycare, a dog that develops sneezing and dripping during spring pollen season, and a pet with one-sided discharge that never resolves. Each scenario points toward different likely causes and different next steps. The outcomes owners usually want are threefold: quick relief for the dog, safe and simple home care when appropriate, and timely veterinary evaluation when needed to avoid worse problems or higher costs later on.

The short version: likely causes at a glance

If you want a short, practical summary before the details: most runny noses in dogs are linked to common, treatable issues, but a few serious causes should prompt rapid veterinary attention. The typical patterns and what they may suggest are:

• Common causes you’ll see first: environmental allergies or irritants, viral or bacterial upper respiratory infections (especially in puppies or dogs in contact with other dogs), and foreign bodies such as grass awns lodged in a nostril.
• Less common but important: fungal infections of the nasal cavity, nasal tumors, and infections that spread from bad teeth into the nose. These tend to produce more prolonged or one-sided signs.
• Urgent versus routine: watery, clear discharge and mild sneezing can often be watched for a few days; bloody, thick, foul-smelling, or persistent unilateral discharge is more concerning and may need prompt veterinary work-up.

How a healthy canine nose actually works

A dog’s nose is designed to filter, humidify, and sense the air. Lining the nasal passages are tiny glands that produce mucus, which is useful — it traps dust, pollen, and microbes and carries immune cells to sites of irritation. That mucus is also moved by tiny hair-like structures so it can drain toward the throat or out of the nostrils.

Mucus is a defensive substance more than a problem. If the nose produces more mucus, it’s usually because the body is trying to clear something out or respond to inflammation. The color and thickness of the mucus can give clues: thin and clear often aligns with irritation or viral causes, cloudy or green-ish may suggest a bacterial component, and bloody or black-tinged material can indicate trauma, invasive disease, or a foreign object.

Breed type affects how the nose drains. Short-faced (brachycephalic) breeds often have crowded nasal passages and less efficient drainage, so they may drip more or have noisy breathing. Long-snouted breeds have more extensive nasal cavities where foreign materials or fungal organisms can lodge. I usually tell owners to consider their dog’s breed when deciding how concerned to be about persistent discharge.

Common situations that trigger nasal discharge in dogs

Triggers for a runny nose are often environmental and seasonal. Pollens in spring and summer, mold spores in damp seasons, and dust mites year-round can provoke allergic-type nasal discharge. Dogs that sniff vigorously along trails may carry more pollen into their nostrils than indoor dogs, so exposure matters.

Indoor irritants also show up frequently. Cigarette smoke, strong cleaning chemicals, aerosolized perfumes, or even room deodorizers can inflame the nasal lining and cause a clear runny nose. Changes in weather and humidity can provoke temporary increases in mucus production: cold dry air often thickens secretions, while sudden humidity can make noses drip.

Finally, exposure to other sick dogs — for example at kennels, dog parks, or grooming facilities — raises the odds of an infectious cause. Puppies and dogs with recent boarding or daycare histories are more likely to have contagious respiratory infections that manifest initially as a runny nose.

Red flags: when your dog’s runny nose is a serious concern

Some signs change a routine sniffle into something that needs immediate veterinary attention. Watch closely for these features, and seek prompt care if you see any of them:

• Any bloody or profuse discharge, especially if it comes from only one nostril, or if the discharge has a very foul smell. That pattern may suggest a foreign body, severe infection, or tumor.
• Systemic signs such as fever, marked lethargy, difficulty breathing, or loss of appetite. These suggest the problem is affecting more than the nose and may need urgent treatment.
• Discharge that persists longer than about a week or that progressively worsens despite simple home care. Chronic, progressive symptoms deserve diagnostic testing rather than continued waiting.

Immediate steps owners can take when you notice discharge

Start with a calm assessment. Gently look at the nose and nostrils: note whether discharge is clear, cloudy, purulent, bloody, unilateral or bilateral, and whether your dog seems uncomfortable when the nose is touched. I recommend cleaning only what you can see and reach — use a soft tissue or cloth dampened with warm water and avoid poking anything into the nostril.

For immediate first aid, wipe away excess discharge, keep the dog warm and comfortable, and monitor breathing and behavior. If the dog is sneezing but otherwise bright, you can often watch for 48–72 hours while reducing potential irritants at home. If the dog shows any red-flag signs above, call your veterinarian right away.

When you contact the clinic, be prepared with specifics. Tell them when you first noticed the discharge, its color and consistency, whether it’s from one or both nostrils, any recent exposures (boarding, other sick dogs), or events (sniffing inside bushes, trauma). It helps to report appetite, activity level, coughing or sneezing frequency, and any fever if you have taken a temperature.

Document what you see. Take clear photographs or short videos that show the discharge, the dog’s breathing, and any relevant behavior. Note the time and date of each observation and any treatments you tried at home (saline rinses, steam, over-the-counter drops). Most vets find this documentation helpful for triage and diagnosis.

At-home care and gentle training strategies to help your dog

For non-urgent cases, small changes at home can reduce symptoms and recurrence. Reduce airborne irritants by vacuuming regularly, using dust-mite-proof bedding covers, and avoiding indoor smoking or harsh household sprays while your dog is recovering. Consider moving meals and bedding away from open windows on high-pollen days.

Humidity control can be surprisingly helpful. A cool-mist humidifier or a short steam session in a bathroom (sit with the dog in a steamy room for 10–15 minutes) may loosen thick nasal secretions and make breathing easier, but avoid prolonged exposure to hot steam that could scald. An air purifier with a HEPA filter may reduce airborne particles that trigger symptoms.

Training your dog to tolerate gentle nose handling and vet transport is an investment that pays off. Teach calm acceptance of a soft cloth over time, reward brief toleration of having the nostril area inspected, and practice loading into a carrier or car calmly. Desensitization and positive reinforcement make veterinary visits less stressful and allow quicker, safer routine home care when needed.

Essential supplies and gear for managing nasal discharge

Keep a small kit ready so you can respond quickly without guessing at treatments. Isotonic saline nasal drops made for pets (or small-animal ophthalmic saline) are safe for gently moistening crusted discharge; place a drop in the nostril and wipe away loosened material. Soft tissues or a clean, damp cloth are useful for exterior cleaning.

Consider a compact cool-mist humidifier or a room air purifier with a HEPA filter suitable for the size of your home. Pet-safe antiseptic wipes can be handy for the surrounding fur, but avoid medicated products inside the nostril unless directed by your vet. Keep your phone or camera ready for documentation and telemedicine consultations.

When to consult a vet or specialist — and what they’ll evaluate

Your primary care veterinarian is the first call for most runny-nose cases. They can often evaluate your dog, prescribe short courses of antibiotics when bacterial infection is suspected, treat allergic inflammation, or advise supportive care. If initial treatment fails or if the problem is complex, referral to a veterinary internist, dental specialist, or an ear-nose-throat (ENT) specialist can be appropriate.

Veterinarians may use several diagnostic tools to pinpoint the cause: a focused oral and nasal exam, rhinoscopy (a small scope to look inside the nose), imaging such as X-rays or CT scans to view deeper structures, and laboratory tests or cultures to identify infectious organisms. Dental X-rays can be crucial when a bad tooth is suspected of spreading infection into the nasal cavity.

For after-hours concerns, many clinics offer emergency services or telemedicine triage. Telemedicine can be useful for quick advice and triage photos, but it may not replace hands-on diagnostics when a foreign body, significant bleeding, or severe respiratory distress is possible.

Sources and further reading on canine nasal health

• Merck Veterinary Manual: Nasal and Paranasal Sinus Disorders in Dogs
• American Veterinary Medical Association (AVMA): Respiratory Disease in Dogs — Client Information
• American College of Veterinary Internal Medicine (ACVIM): Consensus Statement on Infectious Respiratory Disease in Dogs