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Poultry production: Why do chickens snick?

Question: What causes chickens to snick (cough softly or sneeze)?

The causes of snicking can be several poultry diseases or management issues.


  • Mycoplasma gallisepticum and synoviae can both be transmitted vertically from the breeder hens via the eggs to the newly hatched chicks.
  • If this occurs, the chicks will show symptoms at an early age.
  • If the chicks are infected by a field challenge, the symptoms will only be apparent after about 14 days, or even later.
  • Newcastle disease could cause a snick if the field challenge was not virulent, or if chickens were not sufficiently protected.
  • Infectious bronchitis disease can cause chicks to snick if they were not fully protected and there was a field challenge.
  • Avian rhinotracheitis (ART) – if a field challenge occurred, the result would be a snick at the start of the infection.


  • Contaminated vaccine equipment affects the chick’s respiratory system and the result would be snicking.
  • Poor vaccination techniques at the hatchery could cause an irritation in the respiratory system and the result would be a snick.
  • This could result if the Day1 vaccines are applied to chicks that have been held in a hot area, or if they were subjected to over-heating during transport.
  • Chilling or over-heating the chicks during the first two weeks will cause them to snick.
  • Draughts or dry dusty conditions will also cause chicks to snick.
  • High ammonia levels in the chicken house cause the chicks to snick as a result of the damage to the respiratory system.
  • Vaccine reactions will occur if Newcastle or Infectious Bronchitis vaccines are not correctly applied. The result would be damage to the respiratory system and snicks.
  • It is important to note that, if correctly managed, not all snicks result in increased mortality.

Also read:
Poultry production: How to check the general health of your chickens
Egg production: On draughts and egg laying problems
Poultry production: Vaccines – Newcastle disease

  • This article was written by dr. Mick Versfeld and first appeared in Farming SA.

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