Infectious Laryngotracheitis (ILT)

ILT, or Infectious Laryngotracheitis, is a disease of the upper respiratory system that frequently results in severe breathing difficulties.   The disease has a somewhat slow movement from bird-to-bird.   Most birds either die or recover within two weeks of contracting the disease.  Outbreaks continue on a somewhat sporadic basis worldwide.  



  • Chickens 
  • Pheasants
  • Pea Fowl 

Where:  Common though somewhat sporadic, worldwide

When:   14 weeks and older are most susceptible

Why:  Herpes Virus (highly contagious) 

How:  Transmitted by: 

  • Actively infected birds
  •  Latently infected birds (carriers for up to 24 months)
  • Infected objects; people and objects in contact with infected birds


            Common Symptoms:

  • Watery Eyes  (First observable symptom)
  • Conjunctivitis
  • Coughing and gasping
  • Death from suffocation due to blockage of trachea
  • During exhalation, head will rest on breast
  • Difficult breathing
  • Extension of head and neck to help with breathing
  • Nasal discharge
  • Sneezing
  • Shaking of head to dislodge plugs in windpipe
  • Wheezing & gurgling during inhalation
  • Drop in egg production

            Other Symptoms:

  • Blood-tinged mucus expelled from trachea
  • Cawing sound like a crow on exhale
  • Diarrhea
  • Retarded growth
  • Swollen wattles


Treatment:  None.   Extreme caution with biosecurity is recommended.   Antibiotics may be helpful in treatment of secondary bacterial infections.  See "Vaccine" for possible use during an outbreak.       


Vaccine:  Yes (click here for more information) 

  • Recommended in areas where ILT is endemic. 
  • Somewhat controversial, since it can result in latent carriers, and can expose non-vaccinated flocks to the disease. 
  • Can be used during an outbreak to limit the extent and duration. 
  • Vaccine prevents symptoms, but not the virus. 


  • Quarrantine
  • Extreme care in hygiene to prevent movement of the virus between flocks


Also Known As: 

  • ILT
  • LT
  • Laryngo

Affects:  Respiratory system

Clinical Diagnosis:  

  • Physical examination of the trachea during a necropsy.  Swollen windpipe is often clogged with a bloody or "cheesy" mucus plug. 
  • Laboratory detection of the virus and/or antibodies.

Diseases with similar symptoms: 

  • Newcastle Disease
  • Infectious bronchitis
  • Other respiratory diseases

Duration of symptoms:  Usually 10-14 days, however the disease can cycle through the flock for up to 6 weeks.

Incubation:    6 to 12 days from onset to observation of symptoms

Morbidity:  Varies from Low (<10%) occurrence in mild cases, up to 100% in acute cases. 

Mortality:  Varies;  5-70% with an average of 10-20% 

Transmission to people:  No known cases. 


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A righteous man cares about his animal's health...

Proverbs 12:10a