Sinusitis in Chickens: Causes of Swollen Sinuses and Nasal Discharge

Quick Answer
  • Sinusitis in chickens usually means inflammation of the infraorbital sinuses, the air-filled spaces below and around the eyes. It often shows up as puffy cheeks, swollen tissue under the eyes, sneezing, and nasal discharge.
  • Common causes include infectious coryza, Mycoplasma gallisepticum, infectious bronchitis, avian metapneumovirus, and secondary bacterial infection after poor ventilation or ammonia irritation.
  • A chicken with facial swelling, thick discharge, trouble breathing, not eating, or a drop in egg production should be seen by your vet promptly. Isolate affected birds from the flock until your vet advises otherwise.
  • Treatment depends on the cause. Your vet may recommend supportive care, flock management changes, and in some cases prescription antimicrobials or testing to guide treatment.
Estimated cost: $75–$900

What Is Sinusitis in Chickens?

Sinusitis in chickens is inflammation of the infraorbital sinuses, the spaces located below and around the eyes. When these tissues become irritated or infected, fluid and inflammatory material can build up. That can make a chicken's face look puffy or uneven and may lead to nasal discharge, sneezing, or noisy breathing.

In backyard flocks, sinusitis is usually a sign of an upper respiratory problem, not a final diagnosis by itself. Several infections can cause it, especially infectious coryza and Mycoplasma gallisepticum. Viral diseases such as infectious bronchitis or avian metapneumovirus can also affect the sinuses, and environmental stressors like poor ventilation or ammonia can make signs worse or set the stage for secondary infection.

Some chickens stay bright and active with only mild swelling. Others become lethargic, stop eating well, breathe with effort, or develop thick material in the sinuses that can block the eyes from opening normally. Because several contagious diseases can look similar, your vet may recommend testing rather than treating based on appearance alone.

Symptoms of Sinusitis in Chickens

  • Swelling below or around one or both eyes
  • Clear, cloudy, or thick nasal discharge
  • Sneezing or snicking sounds
  • Watery, foamy, or irritated eyes
  • Foul-smelling facial discharge or severe facial swelling
  • Eyes partly closed because swelling is pressing on the lids
  • Noisy breathing, open-mouth breathing, or head shaking
  • Lethargy, poor appetite, weight loss, or reduced egg production

Mild sinusitis may start with subtle sneezing, a damp nostril, or slight puffiness under the eye. More advanced cases can cause marked facial swelling, thick material in the sinus, and reduced eating or drinking. In laying hens, respiratory disease may also show up as a drop in egg production.

See your vet promptly if your chicken has trouble breathing, severe swelling, thick or foul discharge, weakness, dehydration, or multiple birds getting sick at once. Those signs raise concern for a contagious flock problem and may require testing, isolation, and treatment guidance from your vet.

What Causes Sinusitis in Chickens?

The most recognized bacterial cause of swollen sinuses in chickens is infectious coryza, caused by Avibacterium paragallinarum. Merck Veterinary Manual describes infectious coryza as an acute respiratory disease of chickens marked by nasal discharge, sneezing, and facial swelling. In mild cases, birds may only seem quiet with a runny nose. In more severe cases, one or both infraorbital sinuses can become dramatically swollen.

Another important cause is Mycoplasma gallisepticum, which causes chronic respiratory disease in chickens. It can lead to nasal discharge, conjunctivitis, frothy eyes, and ongoing respiratory signs. A key challenge is that mycoplasma often becomes part of a polymicrobial problem, meaning more than one germ may be involved at the same time.

Viral infections can also inflame the upper airways and sinuses. Infectious bronchitis can cause respiratory signs and sinus exudate, and avian metapneumovirus is associated with swollen head syndrome in chickens and can cause nasal discharge and swollen periocular tissues. In addition, severe diseases such as Newcastle disease or avian influenza can include nasal discharge and facial swelling, which is one reason flock-level illness should never be ignored.

Not every case starts with a primary infection. Poor ventilation, damp bedding, dust, and ammonia buildup can irritate the respiratory tract and make chickens more vulnerable to secondary bacterial infection. Stress from overcrowding, introducing new birds without quarantine, or mixing ages can also increase the risk of respiratory outbreaks.

How Is Sinusitis in Chickens Diagnosed?

Your vet will usually start with a flock history and physical exam. Helpful details include the bird's age, how many chickens are affected, whether new birds were added recently, whether egg production has changed, and what the discharge looks like. Because several respiratory diseases overlap, appearance alone often cannot tell you the exact cause.

Testing may include PCR testing, bacterial culture, or sampling material from the infraorbital sinus or upper airway. For infectious coryza, Merck notes that PCR testing of the infraorbital sinus in live flocks can be more accurate than culture. For Mycoplasma gallisepticum, real-time PCR is commonly used. Your vet may also recommend necropsy of a recently deceased bird through a diagnostic lab if flock disease is spreading and a fast answer is needed.

Diagnosis is also about ruling out look-alike problems. Your vet may consider infectious bronchitis, avian metapneumovirus, Newcastle disease, avian influenza, fungal disease, trauma, or foreign material. That is why it is important not to start random medications without guidance. The right test can help your vet choose the most appropriate treatment plan, discuss egg and meat withdrawal times when relevant, and advise you on flock biosecurity.

Treatment Options for Sinusitis in Chickens

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Budget-Conscious Care

$75–$180
Best for: Mild to moderate cases in an otherwise stable bird, especially when one or a few chickens are affected and the pet parent needs a practical first step
  • Office or farm-call exam focused on the affected bird or small flock
  • Isolation of sick birds from the main flock
  • Supportive care plan from your vet, including hydration, warmth, easier access to feed and water, and environmental cleanup
  • Ventilation review and ammonia reduction
  • Targeted prescription treatment only if your vet feels it is appropriate without advanced testing
Expected outcome: Often fair for symptom improvement if the cause is mild and the bird is treated early, but some infectious causes can persist in the flock or create carrier birds.
Consider: Lower upfront cost, but less diagnostic certainty. If the bird does not improve, if multiple birds become sick, or if the flock is used for eggs or breeding, your vet may recommend moving to testing.
Most Common

Recommended Standard Treatment

$180–$450
Best for: Most backyard flock cases with facial swelling, persistent discharge, reduced appetite, or more than one bird affected
  • Veterinary exam plus flock history review
  • PCR or culture-based testing for likely respiratory pathogens
  • Prescription medication plan guided by your vet and local regulations
  • Sinus flushing or drainage when appropriate and feasible
  • Written isolation, sanitation, and monitoring plan for the flock
Expected outcome: Good to fair for short-term clinical improvement in many cases, depending on the organism involved, how early treatment starts, and whether secondary infections are present.
Consider: Higher cost than supportive care alone, but better information for treatment decisions. Some diseases improve clinically yet remain in the flock, so long-term management may still be needed.

Advanced / Critical Care

$450–$900
Best for: Severe breathing difficulty, marked facial swelling, repeated flock outbreaks, valuable breeding birds, or cases where the pet parent wants the fullest diagnostic workup
  • Comprehensive diagnostics through a poultry-savvy veterinarian or diagnostic lab
  • Multiple PCR panels, culture, or necropsy submission for flock outbreaks
  • Advanced supportive care for weak or dehydrated birds
  • Procedures for severe sinus obstruction or caseous material when indicated
  • Detailed flock control plan, including quarantine strategy, culling discussions when appropriate, and egg withdrawal guidance from your vet
Expected outcome: Variable. Individual birds may improve, but prognosis for complete flock clearance depends on the underlying disease. Chronic carrier states are possible with some infections.
Consider: Most complete information and management support, but greater cost and time commitment. In some flock diseases, even advanced care cannot fully eliminate long-term carrier risk.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About Sinusitis in Chickens

Bring these questions to your vet appointment to get the most out of your visit.

  1. What are the most likely causes of this chicken's facial swelling and nasal discharge?
  2. Does this look more like infectious coryza, Mycoplasma, a viral respiratory disease, or a secondary infection?
  3. Should this bird be isolated, and for how long should I separate affected chickens from the flock?
  4. What tests would give us the most useful answer for the cost range I can manage right now?
  5. If medication is recommended, what are the egg or meat withdrawal considerations for my flock?
  6. Are there signs that mean I should bring this chicken back right away or seek emergency care?
  7. What coop changes should I make now to improve ventilation and reduce ammonia or dust exposure?
  8. If this is contagious, what should I do about new birds, shared equipment, and the rest of the flock?

How to Prevent Sinusitis in Chickens

Prevention starts with biosecurity and air quality. Quarantine new birds before introducing them to your flock, avoid sharing equipment with other flocks unless it is cleaned and disinfected, and limit unnecessary traffic into the coop area. Good ventilation matters because stale, damp air and ammonia can irritate the respiratory tract and make infection more likely.

Keep bedding dry, reduce dust when possible, and avoid overcrowding. Sick birds should be separated promptly while you contact your vet. If several birds are affected, treat it as a flock issue rather than an isolated problem. Cleaning feeders, waterers, and high-contact surfaces regularly can also reduce disease spread.

Long-term prevention depends on the cause. Merck notes that prevention of infectious coryza relies on sound management, biosecurity, and vaccination matched to local serovars where vaccination is used. For Mycoplasma gallisepticum, control relies heavily on sourcing birds from healthier flocks and maintaining strong biosecurity. Your vet can help you decide whether testing, quarantine protocols, or vaccination discussions make sense for your specific flock and region.

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