Chicken Eye Infection (Conjunctivitis) in Chickens: Symptoms, Causes and Treatment

Chicken eye infections have multiple causes, and identifying the correct one determines the treatment.

• Mycoplasma gallisepticum (most common): MG is the leading cause of eye disease in backyard flocks, producing foamy eye discharge, swelling, and sinusitis alongside respiratory signs. Carriers spread it continuously.
• Ammonia and dust irritation: High ammonia from wet litter or excessive dust causes chemical conjunctivitis with watery eyes in multiple birds simultaneously. No discharge, no crusting - birds recover with improved ventilation.
• Infectious Coryza (Avibacterium paragallinarum): Causes sudden swollen face, foul-smelling nasal discharge, and eye swelling. Spreads rapidly through the flock.
• Vitamin A deficiency: Produces white, cheesy plaques in the mouth and eyes along with chronic respiratory symptoms. Common in flocks on unfortified scratch-only diets.
• Physical injury: Pecking injuries from flockmates, foreign debris in the eye, or wire abrasions cause unilateral (one-sided) infections with no flock spread.

Start by determining whether one eye or both eyes are affected, and whether other birds are sick.

• One eye only, no flock spread: Likely physical injury or localized infection. Examine carefully for foreign bodies, wounds, or debris.
• Both eyes, multiple birds, respiratory signs: Strongly suggests MG, Coryza, or Newcastle Disease. Isolate and contact a vet.
• Foamy eye discharge: Classic MG sign. Often accompanied by rattling breathing and nasal discharge.
• Watery eyes in whole flock, no discharge: Check ammonia levels and litter moisture first before treating as infection.
• Vet diagnosis: PCR swabs confirm MG vs Coryza vs other causes when multiple birds are affected.

Treatment depends on the underlying cause.

• MG (Mycoplasma): Tylosin (Tylan 50, 0.5 mL IM once daily for 5 days) or doxycycline (25 mg/kg orally daily for 5-7 days). Note egg withdrawal periods apply.
• Infectious Coryza: Sulfonamides (sulfadimethoxine) or doxycycline in water for 5-7 days. Full flock treatment required - all carriers must be treated.
• Topical treatment: Terramycin ophthalmic ointment applied 2-3 times daily can help clear secondary bacterial infection regardless of underlying cause.
• Clean the eye: Gently flush with saline or warm water and remove all crust before applying ointment. Do not force the eye open.

Most chicken eye infections are preventable with good biosecurity and coop management.

• Test before adding new birds: Purchase from NPIP-certified flocks and quarantine new arrivals for 30 days before flock integration.
• Maintain dry litter: Wet litter elevates ammonia and creates bacterial breeding grounds. Refresh litter weekly and add lime as needed.
• Adequate ventilation: Keep ammonia levels below 25 ppm (you can smell it at 25 ppm). Cross-ventilation without drafts is ideal.
• Vitamin A in diet: Ensure the flock receives a complete layer pellet - scratch-only diets cause vitamin A deficiency and increase susceptibility to eye infections.