Gen up on ILT
PUBLISHED: 12:29 15 October 2015 | UPDATED: 12:29 15 October 2015
This one is a bit of a mouthful: Infectious Laryngotracheitis … but henkeepers need to know about it. Victoria reports
ILT is caused by a herpesvirus and mainly affects male, heavy breed chickens and turkeys but can infect other chickens and chicks. Infection with other diseases such as mycoplasma or Infectious Bronchitis, or Vitamin A deficiency and excess ammonia will predispose to more severe disease. Recovered chickens can become carriers, excreting the virus but not showing symptoms.
This disease is getting diagnosed more commonly as more people keep chickens accessed from different sources without quarantining them for two to three weeks, but disease and disease-free areas can exist alongside each other. Transmission via the egg is not known to occur.
Symptoms can be any of the following: conjunctivitis, a nasal discharge, gasping, respiratory effort and/or coughing with blood-stained mucus and blood clots. Affected birds may also sit upon their hocks and egg laying may stop, with a high mortality of around 70% in some flocks. Tracheal plugs of bloody mucus can cause death through the inability of the bird to breathe. Purple facial skin indicates lack of oxygen and can lead to death within three or four days. This disease can show signs in any age of stock but chicks and 3-9 month old chickens are most frequently affected. The early stages of the infection are the most infectious, but older birds may recover from respiratory effort in two to three weeks, likely then to become carriers and infect naïve birds.
Diagnosis is by a laboratory, so if this disease is suspected, your vet will arrange testing. The virus can become latent (hidden) so healthy appearing chickens can still be considered infective (excreting the virus) if the disease has been diagnosed in a flock. Chickens that are coughing up blood do not tend to respond to treatment and should be culled to help prevent further infection.
Newly hatched chicks are free of the disease, thus advice on beginning the day with clean clothes and servicing the youngest stock first is preventative as the disease is spread via the oral and aerosol routes. Mechanical transmission of the disease by personnel, fomites (equipment), animals and birds can occur, so visiting sales and auctions without proper hygiene is potentially risky, let alone purchasing birds that have swollen eyelids or are coughing. Stress is a provocateur of any disease including this one, so keeping stressors low such as poor ventilation, bullying by older chickens or sudden changes in husbandry is important. This would include quarantining new stock, important prevention in any poultry disease, plus culling of those birds coughing bloody mucus. Good husbandry is always helpful, with regular worming with the licensed product plus good ventilation to prevent ammonia encouraging any respiratory problems. Providing dark green vegetables in winter or for a flock that does not range will helpfully increase vitamin A levels.
There is a vaccine given by eye drop after 4 weeks of age up to 18 weeks of age, birds may be re-vaccinated as the vaccine lasts less than one year. There will be wastage of vaccine in small flocks due to the one package size of the vaccine, but it is worth it.
If the disease is diagnosed in the early stages, vaccination provides protection for some months. Any chicken coughing up bloody mucus is not likely to respond to treatment and should be culled.