When to see a vet urgently
Go to an emergency vet immediately if your cat develops:
- open-mouth breathing or clearly laboured breathing at rest;
- a bluish tongue, collapse or reduced consciousness;
- rapidly worsening facial swelling together with breathing difficulty;
- seizures, sudden deterioration in vision or a marked decline in general condition.
Do not try to treat breathing difficulty at home by unblocking the nose. You can find a vet near you.
Overview
A cat's paranasal sinuses, the frontal and sphenoid sinuses, connect to the nasal cavity. Inflammation causes the lining to swell and impairs mucus drainage, allowing bacteria and fungi to multiply. Feline sinusitis often develops secondarily after viral rhinitis, such as herpesvirus-associated rhinotracheitis, calicivirus infection or bacterial rhinitis.
Rhinitis means inflammation of the nasal lining, while sinusitis means inflammation of the sinuses. They often occur together, called rhinosinusitis. The nasal lining helps clean inhaled air. If its structure and clearance of secretions are disrupted, symptoms can continue after the original acute infection has settled.
Chronic inflammation therefore does not automatically mean continuously active viral disease or a single treatable bacterium. However, herpesvirus can remain latent in the body and reactivate, for example during stress. One new sneeze does not reveal whether this is a relapse, new infection or another nasal irritant.
Causes
- Viral infections, including herpesvirus and calicivirus.
- Secondary bacterial infections involving Pasteurella, staphylococci or streptococci.
- Chronic rhinitis.
- Polyps or tumours in the nasal cavity.
- Head injuries.
- Fungal infections, such as cryptococcosis.
An underlying cause may also be a nasal foreign body or a tooth root infection. A single antibiotic course does not remove a polyp, tumour or foreign body obstructing a nasal passage. Repeated similar episodes of nasal discharge therefore need investigation of the cause, rather than simply selection of another course. Several contributing changes may coexist with inflammation.
Risk factors
- Kittens and young cats that have had viral infections.
- Cats with chronic rhinitis or allergies.
- Cats with weakened immunity.
- Cats living in crowded conditions, such as rescue shelters and catteries.
Risk assessment depends on the underlying cause, and this list does not describe one proven risk profile for every sinus disease. Allergic rhinitis or sinusitis is unusual in cats. A polyp is possible in a young cat, for example, but symptoms also occur in adult and older cats. Previous herpesvirus infection does not rule out another concurrent disease.
Typical symptoms
- Persistent or intermittent nasal discharge, which may be mucoid, pus-like or sometimes bloody.
- Sneezing.
- Difficulty breathing through the nose, with a snoring sound on inhalation.
- Changes in the shape of the nose or forehead in chronic disease.
- Lethargy and reduced appetite.
- Watery eyes and conjunctivitis.
Tell your vet whether discharge comes from one nostril or both and whether its character has changed. Sudden one-sided discharge and pawing at the nose can fit a foreign body. Persistent blood or a change in facial shape may raise suspicion of fungal disease or a tumour, for example. None of these observations alone confirms a diagnosis.
A snoring-like sound can result from upper airway narrowing, but laboured breathing is more than loudness. Marked abdominal movement, an extended neck and open-mouth breathing need urgent assessment. A cat with a blocked nose may also have lung or chest cavity disease that you cannot distinguish from sound alone.
A polyp may cause difficulty swallowing, a changed voice, ear scratching or a head tilt. The throat and ears then need examination too. An absence of visible nasal discharge does not mean there cannot be a nasopharyngeal lesion affecting breathing or swallowing.
Complications and consequences
- Inflammation becoming chronic.
- Spread of infection to the eye socket and teeth.
- Osteomyelitis of facial bones.
- Generalised bacterial or fungal infection, rarely.
Consequences depend on the cause. Cryptococcosis, for example, can spread from the nasal area to the central nervous system or elsewhere, but this is not the expected course of every chronic rhinitis case. Dental infection can also be the starting point for nasal symptoms, so an oral finding is not automatically interpreted as infection spreading from the nose.
Diagnosis at the vet
- Clinical examination and history.
- Rhinoscopy and endoscopic examination of the nasal cavity.
- Head X-rays or CT to assess the sinuses and identify tumours.
- Bacterial and fungal culture of discharge.
- Biopsy if a tumour or polyps are suspected.
The history covers symptom duration, previous medicines, treatment response and symptoms in other household cats. Examination assesses facial symmetry, the mouth and teeth, and the ears and eyes when needed. Blood samples may assess general health and procedural safety, but normal routine blood tests alone do not explain persistent nasal discharge.
CT shows changes in the nasal passages, sinuses, bones and surrounding structures more precisely than external inspection alone. However, images cannot always distinguish inflammation from a tumour. Endoscopy can reveal an obstructive lesion and allow suitable sampling. Histological examination of a biopsy shows which cells the lesion contains.
A discharge culture taken only from the nostril's edge may grow bacteria present in the nose without actual bacterial disease. If necessary, a deeper or tissue sample is collected and interpreted alongside other findings. Likewise, a positive herpesvirus or calicivirus PCR may reflect a carrier state and does not alone explain every symptom. Report recent vaccinations too.
An antigen test may be used if cryptococcosis is suspected. A blood result can occasionally be negative in a localised nasal infection, so a tissue sample may still be needed. Even after investigations, the exact original cause of chronic inflammation is not always found. Another aim is to rule out causes with their own targeted treatment.
Treatment
Treatment targets the identified cause. Secondary bacterial infection may need antibiotics, fungal disease needs antifungal treatment, and a mechanical obstruction may need a procedure. Antibiotics do not eliminate viruses. If symptoms return quickly after treatment, the vet reassesses both the diagnosis and the need for further investigations.
A polyp is usually removed under general anaesthesia and the tissue examined to confirm the lesion. Antibiotics may relieve associated bacterial infection but do not remove the polyp itself. Chronic rhinosinusitis, by contrast, does not always have one curative procedure. Treatment benefit is assessed through breathing, appetite and symptom episodes.
A seriously ill cat may need fluids and nutritional support. Relieving breathing difficulty takes priority over lengthy examination or nasal handling. Do not use human nasal drops or leftover medicines yourself. Agree on a method of giving medication that avoids unnecessary handling which worsens breathing or prevents eating.
Home care and monitoring
Keep resting and feeding areas quiet. Offer familiar, appealing food; you can try warming it slightly to strengthen the smell if the cat eats and breathes comfortably. Record whether it actually eats any of the portion. Visiting the bowl or sniffing food alone does not ensure adequate nutrition.
If eating falls markedly or your cat is nauseous, contact the practice. Do not syringe food into a resisting mouth, as this risks food aversion and aspiration into the airways. A vet can arrange a feeding tube if needed. This supports nutrition and does not mean the cat can no longer be treated.
Monitor which side discharge comes from, its character, ease of breathing, eye symptoms, eating and weight. A photograph of facial changes or a short video of breathing sounds may help describe progress. Do not use filming as a reason to postpone an emergency visit. Report new blood, obvious pain or reduced treatment response to the practice.
Prognosis
Long-term rhinosinusitis symptoms can often be relieved even when complete recovery is not possible. Prognosis after removing a foreign body or polyp differs from that for a tumour or disseminated fungal disease. The plan is reviewed according to findings and response. Recurrence alone does not mean that the same medicine or investigation is always the right next step.
Prevention
- Vaccinate against viral infections according to your vet's plan.
- Treat chronic rhinitis and upper respiratory infections.
- Keep allergic diseases controlled.
- Limit contact with sick animals.
- Take your cat to a vet if nasal discharge recurs.
Vaccination reduces the severity of certain viral infections but does not prevent every infection or remove existing structural nasal damage. Hygiene of shared bowls and handling equipment, along with limiting a symptomatic cat's contacts, helps reduce spread. Recurrent symptoms in a vaccinated cat can therefore still need investigation.
Important for cat owners
Sinusitis is more than an unpleasant problem: it can become chronic. Remember that if your cat's nasal symptoms do not resolve within 7–10 days, or there is pus-like nasal discharge, take it to a vet. Early diagnosis and treatment help prevent complications and preserve health.
The 7–10 days mentioned is not a safe waiting period for breathing difficulty, loss of appetite or rapidly worsening symptoms. Contact the vet sooner in these situations. Persistent one-sided discharge or a change in facial shape also needs investigation without assuming ordinary cat flu.
This article provides general information and does not replace veterinary care. If you notice signs of illness in your cat, contact a vet.
Frequently asked questions
Is sinusitis the same as cat flu?
Not exactly. Cat flu can trigger inflammation of the nose and sinuses, but a polyp, dental lesion or fungal disease, for example, may also cause symptoms. Persistent symptoms need assessment of the underlying cause.
Does green nasal discharge mean antibiotics are needed?
Not by itself. Discharge appearance does not reliably distinguish all causes, and bacteria can grow without actual bacterial disease. Treatment decisions depend on general condition, investigations and an appropriate sample when necessary.
Can chronic inflammation clear completely?
It depends on the cause. A removable obstruction may be treatable, whereas long-standing mucosal damage may cause recurrent symptoms. The goals are then comfortable breathing, adequate eating and the best possible daily quality of life.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- Rhinitis and Sinusitis in Cats, Merck Veterinary Manual, accessed 2026-11-05.
- Rhinitis and Sinusitis in Dogs and Cats, Merck Veterinary Manual, accessed 2026-11-05.
- Antimicrobial use Guidelines for Treatment of Respiratory Tract Disease in Dogs and Cats, Journal of Veterinary Internal Medicine / ISCAID, accessed 2026-11-05.
- Guideline for Feline Herpesvirus Infection, ABCD, accessed 2026-11-05.
- Nasopharyngeal Polyps, American College of Veterinary Surgeons, accessed 2026-11-05.
- Cryptococcosis, Cornell Feline Health Centre, accessed 2026-11-05.
- Dyspnea (Difficulty Breathing), Cornell Feline Health Centre, accessed 2026-11-05.
- 2022 ISFM Consensus Guidelines on Management of the Inappetent Hospitalised Cat, Journal of Feline Medicine and Surgery, accessed 2026-11-05.