Runny nose in dogs – rhinitis causes, tests and treatment

Overview

Nasal signs are a starting point for finding the cause

Rhinitis can begin suddenly or persist as chronic disease. It can involve sinus inflammation, or sinusitis. A healthy nasal lining helps filter inhaled air. Impaired lining function exposes the lungs to more dust and microbes than usual.

Persistent discharge does not always mean continuing infection. In idiopathic rhinitis, chronic nasal inflammation is found but thorough investigation identifies no explanatory cause. Lymphoplasmacytic rhinitis describes the inflammatory cell type in a tissue sample. The name therefore does not itself explain what initiated the inflammation.

A study of chronic idiopathic rhinitis included 75 dogs. Median duration of signs before referral was 104 days, ranging from 3–1,954 days. These data concern selected chronic cases, rather than the expected duration of an ordinary runny nose.

Causes

Infection, irritation and material entering the nose

Acute rhinitis can involve a viral respiratory infection. Canine parainfluenza and distemper are possible underlying diseases. Kennel cough can also cause nasal discharge and sneezing. Primary bacterial rhinitis is very rare in dogs. Bordetella is one known exception.

Smoke, irritating gases and dust can inflame the nasal lining. A foreign body lodged in the nasal cavity can irritate tissue locally. Nasal mites can also cause sneezing, reverse sneezing and nasal discharge.

Teeth, fungi and long-term inflammation

An upper tooth root abscess can spread towards a nasal sinus. An oronasal fistula, a connection between the mouth and nose caused by dental disease, can also cause nasal signs. Aspergillus can cause nasal and sinus disease in dogs. A tumour is another possible cause of persistent nasal discharge.

Allergic rhinitis is rare in dogs. The precise mechanism of chronic idiopathic inflammation is unknown. Possible links with allergy, reflux of gastrointestinal contents or the nasal microbiota remain under investigation.

Risk factors

Risk factors depend on the cause. Dusty or smoky air predisposes to nasal irritation. Longstanding dental disease can predispose to an oronasal fistula. Respiratory infections can spread in multi-dog environments.

In the 75-dog chronic idiopathic rhinitis study, median age was 8 years, ranging from 0.5–14 years. Both small and large dogs were included: median weight was 16.0 kilograms, ranging from 2.0–72.7 kilograms. Age or size alone therefore cannot establish the disease.

Typical symptoms

Rhinitis mainly causes nasal discharge and sneezing. Discharge can be clear, mucus-like or pus-filled. Possible observations include:

• Discharge from one or both nostrils.
• Sneezing or repeated bouts of signs.
• Rubbing or pawing at the face.
• Snuffling breathing or snoring.
• Rapid inward snorting, known as reverse sneezing.
• Blood in the discharge.
• Watery eyes and possible conjunctival inflammation.

Sudden one-sided discharge and facial pawing fit a suspected foreign body. Persistent discharge, initially one-sided and later bilateral, can involve a tumour or fungal disease, for example. Fungal nasal disease can be painful enough for your dog to avoid head stroking.

In the chronic case study, 69/75 dogs, or 92%, sneezed. Nasal discharge occurred in 66/75, or 88%. Coughing occurred in 45/75, or 60%. Coughing can therefore be part of the picture even when the main problem appears nasal.

Complications and consequences

Nasal function and quality of life can decline

An inflamed lining and accumulated secretions can narrow nasal passages. Severe narrowing can involve mouth breathing and oxygen deficiency. Chronic disease can also disturb sleep: in one idiopathic rhinitis study, sleep disturbance was reported in 7/13 dogs. Owners nevertheless did not describe these dogs as generally ill. Discharge that seems minor in daily life can therefore impair quality of life.

In the chronic case study, nasal turbinate damage was found in 54/75 dogs, or 72%. These internal nasal structures can be damaged even in idiopathic inflammation, so damage does not automatically mean fungal disease. Another idiopathic rhinitis study found sinusitis in 8/13 dogs, or 62%.

Chest CT showed changes consistent with pneumonia in 14/66 examined dogs with chronic rhinitis, or 21%. However, a causal link between nasal discharge and pneumonia remained unconfirmed. Coughing with fever, weakness or loss of appetite requires assessment for pneumonia.

Diagnosis at the vet

The mouth, nasal cavity and sinuses are examined together

Your vet reviews the history of signs and examines general condition. The mouth and teeth are also examined with nasal signs. Tooth root disease can be missed by a superficial mouth examination alone.

CT shows changes in the nasal cavity, sinuses and bony structures. It can also investigate deeper dental disease. Nasal endoscopy, or rhinoscopy, helps look for a tumour, foreign body, parasites and fungal changes. Sinuses may contain changes beyond the reach of ordinary endoscopy.

A tissue sample assesses inflammation type and looks for findings such as fungal structures. An idiopathic diagnosis requires exclusion of other explanatory diseases. Finding inflammatory cells alone therefore does not complete the whole investigation.

In the chronic case study, both sides were sampled in 62 dogs. The same diagnosis was obtained on both sides in 54/62 cases. In the remaining 8 cases, tissue findings differed between sides.

Laboratory results are interpreted alongside other tests

Routine blood tests may show only minor abnormalities in different nasal diseases. They do not reliably distinguish idiopathic rhinitis from other nasal cavity diseases. A positive bacterial culture may grow normal nasal microbiota. Culture may be more useful if your dog is systemically ill and significant secondary bacterial growth is suspected.

A negative Aspergillus antibody result does not exclude fungal nasal disease. A positive antibody result can instead reflect environmental exposure without actual infection. Fungal culture can be positive in up to 30% of healthy dogs. Fungal disease is therefore assessed by combining imaging, endoscopy and targeted samples.

In one study, positive allergen-specific IgE screening neither confirmed idiopathic rhinitis nor predicted corticosteroid response. This screening is different from a thorough allergy investigation.

Treatment

Treatment targets the identified cause

For mild, recent-onset rhinitis, measures to relieve signs may suffice. Your vet assesses whether home monitoring is suitable or an examination at the practice is needed. In bacterial infection, an antimicrobial may be chosen according to findings. Antibiotics do not work against viruses. Uncomplicated kennel cough usually resolves untreated within 7–14 days. This time concerns kennel cough, rather than every cause of nasal discharge.

Fungal disease needs treatment targeting the identified fungus. Nasal aspergillosis is treated with local antifungal therapy. Before this, CT assesses the integrity of the cribriform plate between the nasal cavity and skull. Radiotherapy can be a key option for a nasal tumour. Your vet plans all medicines and nasal treatments.

Chronic idiopathic inflammation may need treatment trials

Responses in idiopathic rhinitis vary. Treatments used include NSAIDs, corticosteroids and, in selected cases, other medicines affecting the immune response. Mucus clearance can be supported with measures such as veterinary-planned humidification. Nasal lavage and mucus removal can make small foreign bodies and tumours easier to detect during endoscopy. However, symptom relief from these measures may be brief.

The outcome at last contact was available for 63 dogs with chronic idiopathic rhinitis. Of these, 14/63 were in remission and 38/63 had improved signs. Signs were unchanged in 9/63 and worse in 2/63. Remission meant no medication and signs so mild that the owner sought no further treatment. It therefore did not mean every sign had disappeared completely.

Median follow-up was 237 days, ranging from 14–1,701 days. Treatments varied and were also used concurrently. Outcomes therefore describe the end of the overall care pathway, rather than a benefit definitely caused by one medicine.

Prevention

Nasal irritation can be reduced by avoiding smoke, dust and irritating gases. Investigating dental disease forms part of addressing nasal signs, as a root abscess can spread towards the nose.

Appropriate vaccination reduces illness associated with some respiratory infections. Concurrent infection with several respiratory microbes is common in kennel cough. A dog vaccinated against kennel cough can still develop signs and shed pathogens. The cause of idiopathic rhinitis is unknown, limiting cause-specific prevention. There is therefore no shared preventive measure for every form of rhinitis.

Important for dog owners

Watch discharge, breathing and everyday wellbeing

Record whether one or both nostrils discharge and what the fluid looks like. Include sneezing, coughing, blood, facial rubbing and situations that worsen signs. Report previous medication, dental problems and possible foreign body exposure. Apparently one-sided discharge does not necessarily mean disease on only one side: in an idiopathic rhinitis study, bilateral tissue samples showed inflammation in every dog examined.

Assess sleep, appetite and willingness to exercise too. At agreed follow-up, changes in signs and the need for further tests are reviewed. Keep investigation results and medicine names to give a clear picture of response.

With breathing difficulty, transport your dog calmly in a cool car. You can phone the emergency vet beforehand so they can prepare for arrival. Warning signs include a bluish colour, visible breathing effort and collapse.

Frequently asked questions

Can dust alone cause a dog's runny nose?

Dust, smoke and irritating gases can cause acute inflammation of the nasal lining. However, a foreign body, infection or another nasal cavity disease can cause similar signs. Persistent or recurrent signs need veterinary assessment of their cause.

Does discharge from one nostril mean a foreign body?

Sudden one-sided discharge and facial pawing raise suspicion of a foreign body. However, persistent one-sided discharge can also involve fungal disease or a tumour. Location helps plan investigation, but the cause is established using other findings and nasal imaging or endoscopy where needed.

Does a runny nose need an antibiotic?

Not automatically. An antibiotic may be indicated for confirmed or suspected bacterial infection. It does not work against a virus. In chronic idiopathic rhinitis, cultured bacteria may represent normal nasal microbiota. Your vet therefore assesses the need for medication using investigations and general condition.

Does a positive allergy test mean allergic rhinitis?

Not directly. Positive allergen-specific IgE screening did not help confirm idiopathic rhinitis or predict corticosteroid effectiveness in one study. This screening differs from a complete allergy investigation. Positive IgE results also occurred in dogs with other nasal diseases. Allergic rhinitis is rare in dogs.

Can chronic rhinitis resolve completely?

Some dogs obtain substantial relief, but responses vary. In one study, 14/63 dogs were in remission and 38/63 had improved signs at last contact. In remission, medication had stopped and signs were so mild that no further treatment was sought. Complete absence of signs was therefore not required for this category.