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Ammonia Toxicity

Other Names: Ammonia Blindness, Ammonia-induced Conjunctivitis, Keratoconjunctivitis, Ammonia Burn

Ammonia toxicity is an inflammatory eye condition in chickens. It is caused by exposure to prolonged or high amounts of ammonia fumes. Ammonia concentrations above 25 ppm are toxic to chickens.

Ammonia has a distinctive, pungent smell and is known for its irritating effect on the respiratory system, eyes, and mucus membranes. Besides its incorporation into many household and industrial cleaners and window-cleaning products, ammonia is naturally produced within animal droppings.

When chickens are housed in confined, indoor spaces with accumulated manure, they are often exposed to high concentrations of ammonia, especially when the area is infrequently or inadequately cleaned out on a regular basis. There are several factors that affect the ammonia concentration in the air in chicken coops which include the type of bedding substrate used, bird activity, the frequency of manure removal, humidity level, surface area of the stored manure, ventilation rate, manure handling, the number of chickens, and the pH of the manure produced.

Ammonia toxicity usually occurs in both of the chicken's eyes. The main clinical symptom is the inflammation of the cornea and conjunctiva of the eye (conjunctivitis). Young, growing chicks are more susceptible to ammonia damage then adult chickens. Chickens are more prone to developing ammonia toxicity during the winter season, due to increased time spent indoors, with reduced ventilation and accumulated manure.

Clinical Signs

Crusty eyes
Swollen eyelids
Rubbing heads against wings
Gray cloudy-looking cornea
Reddened eyes
Sensitive to light


  • History
  • Clinical signs
  • Eye exam

Reported Cases

  • Case 1: Ammonia Toxicity in a Chickens Excess ammonia was the suspected cause of respiratory signs and increased mortality in a flock of 20-month-old layers and conjunctivitis and swollen eyes in a flock of 26-day-old broiler chickens. Ammonia damages the tracheal, sinus, nasal, conjunctiva and corneal epithelium, removes the cilia from the respiratory epithelium and causes excess mucus production which was found in both groups of birds submitted to the diagnostic lab. Ref

  • Case 2: Ammonia Toxicity in a Broiler chicks Ammonia toxicity was diagnosed in several 18- to 21-day-old broiler chicks. The chicks appeared sleepy and had their eyes closed. The eyelids were edematous and congested and the cornea had erosions. Reused and wet litter in combination with poor ventilation was the main contributing factors for this condition. Ref

  • Case 3: Ammonia Toxicity in a Chickens Corneal erosions due to increased ammonia levels in the house was diagnosed in 13 to 15-week-old breeder replacement chickens. The birds were reluctant to open their eyes, had swollen and reddened eyelids and the corneas had roughened surface. Increased ammonia in the house was attributed to increased moisture in the litter and decreased ventilation due to a cold spell experienced over a one to two week period. Ref


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Yucca (Yucca schidigera) extractAdd to diet at 100-200 mg/kg of feed to reduce ammonia levels released by the birds.M Saeed et al., 2018; H Chepete et al., 2012; M Cabuk et al., 2004;
Management changesClean/change coop litter/bedding more often, consider switching to a different type of material. Peat works best for reduction of ammonia levels.Mönki J, Saastamoinen M, Karikoski N, et al., 2021



  • Add 100 g/kg of natural zeolites (clinoptilolite) to the bedding litter to help reduce ammonia levels.
  • Ensure proper ventilation and provide dry, clean bedding that is regularly changed.
  • Do not overcrowd birds
  • Add yucca (Yucca schidigera) extract to diet of birds.
  • Use peat as a substrate material. It has a good capacity to bind ammonia, a feature based on its naturally low pH value.


It depends on how quickly it is discovered and treated.

Scientific References

Good Overviews


Risk Factors

  • Build up of droppings in an enclosed, poorly ventilated area such as chicken coops
  • Increased moisture
  • Increased time spent indoors, such as during the winter season