Written by: Dr. Jacquie Jacob, University of Kentucky

Laryngotracheitis (LT)—also called infectious laryngotracheitis (ILT) and laryngo—is a virus that affects chickens and pheasants. Chickens 14 weeks and older are more susceptible to this illness than are young chickens. As a result, most outbreaks occur in mature hens. Outbreaks have occurred in flocks of broilers older than three weeks of age. Improper use of vaccines is believed to cause this disease in broilers.

LT can be spread mechanically from flock to flock by contaminated clothing, shoes, tires, and so on. LT is spread from bird to bird through the air on respiratory secretions. Infected birds cough and release the virus, which uninfected birds then inhale. Birds that recover from this illness should be considered carriers for life.


The first clinical sign of the disease that producers typically noticed is watery eyes. Affected birds remain quiet because breathing is difficult. Affected birds progress to coughing, sneezing, and shaking of the head to dislodge cheesy material (referred to as a plug) in the windpipe. Birds typically extend their heads and necks to facilitate breathing. Inhalation produces a wheezing and gurgling sound. Many birds die from suffocation as a result of the plugs in their windpipes.


You can administer antibiotics to infected birds to prevent secondary infections, but the antibiotics will have no effect on the virus. For small flocks, you can use swabs to remove plugs from gasping birds. It is important to remember, however, that infected birds will continue to be carriers of the disease.


To prevent the spread of the virus, it is important to incinerate dead birds. Implementing and maintaining an effective biosecurity program will also help prevent the introduction and spread of the disease. A vaccine is available to prevent infection. For small flocks, it is recommended that the vaccine be administered to each bird with the eye-drop method.


Overview of Infectious Laryngotracheitis in poultry. Merck Veterinary Manual.