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Ammonia Toxicity

Ammonia Blindness, Ammonia-induced Conjunctivitis, Keratoconjunctivitis, Ammonia Burn

Ammonia is an invisible, water-soluble, colorless alkaline gas with a very distinct odor, and is listed as a toxic substance by the Agency for Toxic Substances and Disease Registry. Besides its incorporation into many household and industrial cleaners and window-cleaning products, ammonia is naturally produced within poultry droppings. Ammonia has a distinctive, pungent smell and is known for its irritating affect on the respiratory system, eyes, and mucus membranes of humans. As a result of prolonged or frequent exposure to ammonia, both humans and chickens are at risk of developing a chronic sinusitis. In humans, this causes them to become desensitized by the smell of ammonia, preventing them from being able to readily detect it in their surroundings.

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 and poultry houses, 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.

Similar to humans, ammonia is also irritating and toxic to a chicken's respiratory system, however even moreso, considering the difference in a bird's respiratory system to humans and other mammals. Ammonia toxicity refers to an inflammatory eye condition in chickens, caused by exposure to prolonged or high amounts of ammonia fumes. Ammonia concentrations above 25 ppm is toxic to chickens. 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.

Cases of Ammonia toxicity reported in flocks
AffectedHistoryClinical signsDiagnostic FindingsTests usedRef
13- to 15-week-old chickens raised as breeder replacementsIncreased 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. reluctancy to open their swollen and reddened eyelids.Corneal erosions; appeared as roughened surface of the corneal during necropsy.NecropsyCAHFS Connection, March 2016
20-month-old laying hens from commerical flocksIncreased mortalityRespiratory signsAmmonia damage to the tracheal, sinus, nasal, conjunctiva, and corneal epithelium; removed cilia from the respiratory epithelium, resulting in excess mucus production.NecropsyCAHFS Connection, April 2013
26-day-old commerical broiler flocks Conjunctivitis and eye swelling.Ammonia damage evident in the tracheal, sinus, nasal, conjunctiva, and corneal epithelium. During necropsy, removal of the cilia from the respiratory epithelium resulted in excess mucus production.NecropsyCAHFS Connection, April 2013

Clinical Signs

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


  • History
  • Clinical signs
  • Eye exam


Management changesClean/change coop litter/bedding more often, consider switching to a different type of material. Peat works best for reduction of ammonia levels.
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.
Topical antibiotics



  • Add 100 g/kg of natural zeolites (clinoptilolite) to the bedding litter, to help reduce litter moisture and ammonia levels.
  • Ensure proper ventilation and provide dry, clean bedding that is regularly changed.
  • Do not overcrowd birds


It depends on how quickly it is discovered and treated.

Scientific References


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