When to Worry About Your Dog’s Runny Nose

If your dog is having excessive nasal discharge, there are a number of possible causes. Find out what your dog's runny nose could mean here.


It’s that time of year again. Runny noses and sneezes abound for us humans, as new plants bloom in the fall. But did you know that your dog can suffer a runny nose too?Dog runny noses are more correctly called nasal discharge. It can run the gamut from clear and watery to thick and purulent. The appearance and frequency of nasal discharge in dogs can tell you much about the underlying cause.

Could My Dog Have Allergies? In Short, Yes.

A thin, watery discharge without color or odor is likely a sign of mild irritation in the nasal cavities. This can occur with seasonal allergies or other causes of inflammation within the nose such as an inhaled foreign object (grass and seeds). In some cases, antihistamines will clear up the discharge without further incident. Dogs do sometimes respond to environmental allergens just as humans do—with red, watery eyes, sneezing, and a runny nose.

More Serious Causes of Dog Runny Noses

In cases where the discharge is thick, has odor, or discoloration with blood or pus, more serious causes are suspected. If this is the case, your veterinarian will do a thorough investigation of your dog’s recent history (any history of kennel boarding, grooming, dog park visits, or doggy daycare? Any exposure to dogs otherwise?) and a physical exam. They will also review your dog’s vaccination status to make sure that they are current.

Once the initial history and exam are finished, your veterinarian will discuss possible causes of your dog’s runny nose. If both nostrils are involved, the causes are frequently different than if only one nostril. Both nostrils points to a more generalized cause while one nostril points to a localized source. If the discharge is clear, thin, and watery, your veterinarian may try antihistamines and monitoring at home for any other signs.  If none develop, and your dog seems otherwise healthy, it may be normal for a small amount of discharge to occur. No further treatment may be needed.

If the discharge continues or worsens, then more diagnostics are needed. In the case of unilateral discharge (one nostril involved), the causes could include an inhaled foreign body such as grass or grass awns leading to rhinitis, a fungal infection, or a nasal tumor. Your veterinarian will likely try a course of antibiotics. If no response occurs, then the next step is generally a rhinoscopy. In this procedure, your dog will be anesthetized, a camera will be inserted into the nostril to look at the area, and samples will be taken for culture and biopsy. In some cases, a CT scan of the head is needed to make a definitive diagnosis.

If both nostrils are involved, this points to a more generalized problem such as a viral or bacterial infection. Dogs are prone to both especially if they board at a kennel, visit the dog park, or go to grooming facilities.

Canine influenza is becoming more common in the dog population. In this case, concurrent with the runny nose would be a fever, sneezing and coughing, lethargy, and often lack of appetite. Pneumonia is a possible side effect. Canine kennel cough, a common bacterial complex, can also cause a nasal discharge. This generally occurs when the disease progresses to pneumonia.


In the case of a dog with no other symptoms and some clear nasal discharge, a runny nose is not cause for immediate concern. It is when your pet develops other symptoms such as red, watery eyes, sneezing, coughing, fever, lack of appetite, or lethargy that a trip to the veterinarian is warranted.

Looking for more? Check out this page on runny noses in dogs.

Image credit: fongleon356 – Shutterstock ID: 392683123


  1. Hello,

    Thank you for the article. My female lab has chronic nasal discharge (rhinitis) to both nostrils. Discharge started mild and as she got older, the discharge got thick green and accompanied with sneezing and lethargy. Rhinoscopy found no polyps or foreign objects. Culture found Pasteralla so antibiotics with a steroid was provided. This cleared up discharge for awhile, her energy returned but as time went on it comes back. After taking allergy meds, apoquel and regiment of other meds nothing helped. Now she has an inhaler (flovent HFA 100mcg) and takes Azithromycin (250mg) every other day but still has thick yellow discharge but not as much or green and reverted sneezes alot. Ive spent thousands over the years and seem to get nowhere. Any other ideas?

  2. Hello,

    My dog has a runny nose on both nostrils. Although her nasal discharge is mild and thin, her body is cold. Is there any danger to that? How should I help her?

  3. My dog had a thick muddy mucous then lead to bloody nose. Started with one nostril and ended up bleeding with other nostril. Vet prescribed antibiotics and steroids but still did not clear up. Two sets of antibiotics prescribed still did not cure. Unfortunately my dog just past 3 days ago. He threw a seizure 1 week ago and died 4 days after the seizure. He was 12 years old and had arthritis. So sad.

  4. Nasal mites can cause sneezing and discharge. They are a possibility that can be overlooked as vets seem to think they aren’t common.

  5. My rescue large lab/shepherd mix has had nasal discharge from the beginning. It is thick and not clear. Whenever he sneezes out it comes! I constantly have tissues with me and it’s like wiping the nose of a toddler. He has been on antibiotics (no help) and he gets allergy shots now – we’ll see if those help as time goes on. It’s very frustrating for sure. Also I’m sure this contributes to his breath smelling!

  6. My dog had his K9 teeth left top removed due to cavity. 6 months after his dental procedure and with the pollen his left side of his nose has a discharge that went from clear to thick mucus. He had the allergies injection but he still has discharged and ear infections so

  7. My collie was diagnosed with nasal lymphoma. This article brought back a lot of bad memories of what he had to go through. Don’t waste anytime getting your dog checked.

  8. This is for Mary Ann, I just saw your post. I don’t understand why no one replies to our posts when they tell you to ask a question. I am not a vet but I have been a vet tech and have worked with dogs for a long time. The muddy mucus discharge may be was an indication of old blood with the mucus it gave it a brownish color. Your baby may have had a tumor in the lungs which would cause nose bleeding or a brain tumor or something in the sinus cavity. Three weeks ago I was grooming a Shih Tzu that started sneezing and the nosebleed was terrible. It ended up being a tumor in the lungs. I am so sorry for your family member you’re little joy that you lost. I am disappointed that whole dog journal didn’t give you any kind of response. Dog journal should have at least told you to follow up or get a second opinion. Other than that it’s a great little magazine I loved getting it. God bless and stay well

  9. My 8 year-old 50lb mix also has had chronic yellow-mucus for the past 6 months. First, vet prescribed antibiotics. Then, nasal scope to remove any foxtails and more antibiotics. Then “deeper” nasal scoping surgery and more antibiotics and steriods. It is now suggested that the cause may be a fungal infection.

    How is fungal infection diagnosed?

    I see posts that suggest dental infection may be the cause and he may have a bad tooth in front. Has anyone had a bad tooth removed and then constant mucus cleared up?

    • I’ve been going through this with my husky since February 2019. Started with coughing for about a month before any nasal discharge developed. Ct scan, rhinoscopy, no results. Lung xrays and blood work every couple months, antibiotics here, antibiotics there. Randomly started having focal seizures, put him on gabapentin which helped stop that. Had a bad tooth so we got it removed in March 2020. No improvement. Tried antihistamines, no luck. Apoquel did nothing. Developed a rash on his face, looks like zrd so we start him on zinc. Rash gets infected after being scratched at, tried treating with an ointment and antiseptic wipes for a couple weeks. No improvement so we started clindamycin three days ago. Yesterday his nasal discharge was bloody, still bloody this morning. This was one of the healthiest dogs I’ve ever had up until this started. Very frustrating spending thousands and getting no answers. Rhinitis is the only diagnosis I’ve gotten but that doesn’t account for any of these other symptoms.

  10. I ended up going to a specialist and he recommended getting an MRI, but of course those are super expensive and I was told it would be about $850. There is a pretty exciting treatment for fungal infections using Vagisil and a scope. I would think if nothing else can be diagnosed then that definitely could be an option, but again it is super expensive and if the dog doesn’t have a fungal infection then you just spend a lot of money for no reason. I think my dogs are going through this, but it is allergies. It really sucks when vets can’t tell you what is going on.

    • My dogs are coughing and instead of discharge coming out. He like a little kid. He sucks them back up. Then that’s when he starts to cough. I thick he coking on mucus! But over all its allergys! Just push fluids and allergy pills.


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