Nasal discharge that lasts more than 4 weeks is a different disease from the 7–10 day cold most cats get as kittens. Chronic rhinitis in cats is usually permanent damage to the nasal turbinates after a viral infection, and it is managed, not cured. Antibiotics help only when bacteria are secondary to that damage, which is why repeated 3-week courses change nothing except the cat's gut flora.
Four weeks is the dividing line
Acute upper respiratory infection (URI) from feline herpesvirus (FHV-1) or calicivirus runs 7–10 days, peaks at day 3–4, and clears without treatment in most adults. Signs that persist past 4 weeks, or that return every 3–6 weeks, move into a different list. The most common cause is post-viral chronic rhinosinusitis: inflammation and secondary infection remodel the delicate turbinate bones, and CT shows scroll loss, thickened mucosa and trapped secretions that no antibiotic can reach.
The second common cause is FHV-1 reactivation, which brings sneezing with ocular signs together — see long-term feline herpes management for the latency and stress-trigger side of that picture. If the cat hunts or eats raw meat, add toxoplasmosis to the list of causes of chronic respiratory signs, covered in toxoplasmosis in cats.
Building the differential before treating
| Cause | Typical signal | First test |
|---|---|---|
| Post-viral chronic rhinosinusitis | Bilateral, worse on one side, URI as a kitten | CT, nasal lavage cytology |
| FHV-1 reactivation | Sneezing plus conjunctivitis or corneal ulcer | Ocular exam, fluorescein |
| Foreign body | Sudden unilateral, bloody, violent sneezing | Sedated nasal exam |
| Nasopharyngeal polyp | Young cat, stertor, head shaking, ear disease | Otoscopy, CT |
| Neoplasia | Cat over 9, unilateral, epistaxis, facial swelling | CT plus biopsy |
| Oronasal fistula | Bad breath, one-sided discharge, dental history | Oral exam under sedation |
| Cryptococcosis | Outdoor cat, nasal swelling, skin nodules | Antigen test, cytology |
Two features split the list fast: symmetry and age. Bilateral discharge in a cat with a URI history points to post-viral disease. Unilateral discharge, blood, or facial deformity in a cat over 8 points to tumour, foreign body or dental disease, and those cats need imaging, not another antibiotic.
Examining a cat that will not cooperate
Awake examination gives you maybe 40% of the information. Sedation with dexmedetomidine or alfaxalone lets you open the mouth, check the hard palate for a fistula, look behind the soft palate, and pass an otoscope into both nares. Record respiratory rate at rest, character of the discharge (serous, mucoid, purulent, bloody), and which nostril is worse. Photograph the nostrils each visit; owners underestimate the change.
Flat-faced breeds such as Persians have compressed nasolacrimal ducts and narrow nares, so they tear and snore from anatomy alone. Breed background is worth checking in the site breed library before you attribute everything to infection.
What a nasal flush actually does
A flush is diagnostic and briefly therapeutic, not a cure. Under general anesthesia with a cuffed tube, 5–10 mL of warm sterile saline is pushed into each nostril and the return fluid is collected for cytology and bacterial culture. It removes pus and plugs, opens passages for a few days, and gives a sample that a swab cannot: swabs from the front of the nose mostly grow commensals.
Expect 3–7 days of improvement, sometimes 2 weeks. Repeat flushing every 4–6 weeks is a sign the underlying problem has not been addressed. Skip it when there is active epistaxis, a suspected cribriform plate fracture, or severe dyspnea; the risks are aspiration, hemorrhage and post-anesthetic swelling that closes the airway.
Nebulization at home, done properly
Use 0.9% saline, 10–15 minutes, twice a day, in a closed carrier or a steamy bathroom. Never add essential oils, eucalyptus or tea tree — they are toxic to cats and cause hepatic injury. Do not put antibiotics in the nebulizer as a routine; they do not reach the turbinates in useful concentrations and they select resistant bacteria.
Warm mist loosens crusts, soothes the mucosa and makes sneezing productive. Wipe the nose with a warm damp cloth afterwards and clean the mask between uses. The evidence for nebulization is modest and mostly symptomatic, but it is low-risk and owners notice fewer bloody crusts within 5–7 days.
How long antibiotics should run
Treat secondary bacterial infection for 7–10 days: doxycycline 5 mg/kg twice daily, or amoxicillin-clavulanate 12.5–25 mg/kg twice daily. Azithromycin 5 mg/kg once daily for 3–5 days is an alternative when pills are impossible. Culture and sensitivity are worth the money after the second course, because the bacteria in chronic rhinitis are often Pseudomonas or Staphylococcus that a first-line drug will not touch.
Stop at 10 days if there is no clear improvement. A cat that has had 3 or more courses in 12 months, or any course longer than 3 weeks without culture, needs imaging rather than a fourth prescription. Long courses are only for documented biofilm infection, with a culture and a recheck at 2 weeks.
When to book the CT
Book it for unilateral signs, epistaxis, facial asymmetry, neurologic signs, no response after 4–6 weeks of correct treatment, or before any surgical plan. CT under anesthesia takes 10–15 minutes, costs roughly 400–900 USD at a referral hospital, and shows soft-tissue masses and early bone loss that plain radiographs miss. If CT confirms a polyp, removal is often curative; if it shows a tumour, you have a diagnosis instead of a sixth antibiotic.
Red flags and long-term care
- Blood from the nose that fills a tissue in under a minute
- Open-mouth breathing, or a resting rate above 40 per minute
- Facial swelling, a bulging eye, or one nostril completely blocked
- Weight loss of 10% or more over 3 months
- Any of the above with a cat over 9 years old
For the chronic, stable cat: dust-free litter, humidity at 40–50%, no cigarette smoke, HEPA filter in the room where it sleeps, and saline drops twice daily. Keep the cat at a body condition score of 5/9, because obesity worsens dyspnea. Lysine has no consistent benefit in trials and is not worth the daily fight.
Five steps for the next month
- Write down the start date and the character of the discharge; 4 weeks changes the plan.
- Book a sedated exam with otoscopy and an oral check before any new antibiotic.
- Do one nasal flush with cytology and culture if discharge is thick or unilateral.
- Nebulize with saline twice daily for 14 days and photograph the nose weekly.
- Ask for CT if signs are unilateral, bloody, or unchanged after 6 weeks.
Frequently asked
Is chronic rhinitis in cats curable?
Usually not. When the turbinate bones have been remodeled by a past viral infection, the damage is permanent and the goal becomes control: keeping secretions thin, treating secondary bacterial flares for 7–10 days, and reducing triggers. Cats managed this way often live normal lives, but owners should expect intermittent sneezing and discharge rather than a cure.
How often can a cat have a nasal flush?
One flush is diagnostic and gives 3–7 days of relief. Repeating it every 4–6 weeks means the underlying cause has not been identified, so the next step is imaging rather than another lavage. Flushing is avoided during active nosebleeds, suspected cribriform plate fracture, or severe respiratory distress.
Do antibiotics help chronic cat rhinitis?
Only for secondary bacterial infection, and only for 7–10 days at a time. Antibiotics cannot reach secretions trapped inside remodeled turbinates, and repeated courses select resistant bacteria. After 3 courses in a year, or any course beyond 3 weeks without a culture, the money is better spent on a CT scan.