March 1, 2019

We all know that with winter comes cold weather and with cold weather comes copious amounts of respiratory challenges for the broilers/pullets/layers in your care. In this quarters article, I wanted to briefly go over some of the most common respiratory issues poultry may face, as well as, some things you can do to try and prevent and treat once they get them.


As we close the houses to keep heat in for the winter, we inevitably increase both dust and ammonia inside. Both these things alone or paired together can be detrimental to the bird’s respiratory tract. Ammonia at high enough levels can cause cilia stasis (paralysis of the cells that beat to remove foreign material, dust, and pathogens from the trachea). Too much dust can overwhelm even the heathiest immune systems, causing upper respiratory irritation or progression to infections. Challenges with dust and/or ammonia can allow pathogenic bacteria to enter the lungs and airsacs, causing morbidity or mortality and likely contributing to condemnations at the plant.

Common Diseases

While there are numerous respiratory diseases that can affect broilers, the most common of those diseases are Infectious Bronchitis Virus (IBV) and Newcastle Disease Virus (NDV). These two viruses can cause varying degrees of clinical signs based on the serotype in the case of IBV and pathotypes in the case of NDV. Both respiratory diseases can also allow otherwise non-pathogenic bacteria to cause clinical disease.


There are multiple serotypes of bronchitis virus that can affect chickens. Most of these serotypes primarily affect the respiratory tract of the bird, but certain strains can also have a predisposition for the kidneys (cause flushing and wet floors) or the reproductive tracts (false layer, egg shell abnormalities, drops in egg production). Although all the serotypes are the same virus, slight genetic and structural differences in the virus make them different enough from one another that one vaccine cannot protect against all types. Therefore, there are multiple vaccine options for IBV. Although proper management and biosecurity are important to prevent IBV in your chickens, it is often crucial that you vaccinate the birds in your care against the challenge strain of IBV specific to your area. This often requires the help of a diagnostic lab.


There is only one serotype of this virus, but multiple pathotypes (lentogenic-less pathogenic, mesogenic- moderately pathogenic, velogenic- severely pathogenic). The US commonly has circulating strains of lentogenic type NDV, which are usually well controlled with commercially available vaccines. As many already know, there has been outbreak of velogenic NDV in California and Utah since last year. State and federal officials are working to eradicate this strain as its effects on poultry is/can be detrimental. NDV, depending on the severity, can affect the respiratory tract, gastrointestinal tract, neurologic system, and reproductive system (drop in egg production, egg shell abnormalities). Like IBV, it is often vital to have your local diagnostic lab help with the diagnosis of this virus.

The other two more common respiratory diseases in broilers are Infectious Laryngotracheitis Virus (ILT) and Aspergillosis.


ILT is a herpes virus that can cause severe infections. Most cases in the US result from vaccinal strains of ILT over true field challenge, but the damage this virus does to the respiratory tract (specifically the trachea) can cause extreme morbidity and mortality. The classic clinical picture for ILT are bloody trachea, but sometimes you may only see conjunctivitis. There are multiple vaccine available for prevention of this disease, but many states require pre-approval to use certain vaccines because of the likelihood of the vaccine to cause clinical disease if not used properly.


Aspergillosis is a fungal infection caused by exposure to fungal spores that become inhaled and cause respiratory distress. Birds typically get exposed in one of two ways: exposure to fungal spores at the hatchery or exposure to spores on farm (often from certain litter sources). The easiest way to prevent this disease is with proper sanitation and monitoring at the hatchery and sourcing litter only from reputable suppliers.

Uncommon Diseases

Some less likely to occur, but important diseases to know about include Avian Influenza (AI), Mycoplasma gallisepticum (MG), Mycoplasma Synoviae (MS), and Infectious Coryza. All these diseases are best prevented with proper biosecurity and require the help of your local lab system to diagnose.


For many of the bacterial diseases, the use of antibiotics can be curative or at least reduce the severity of clinical signs. We have less options for treatment of viral diseases. ABF, Organic, and commercial egg layers also have significantly less options for therapy. In instances where antibiotics cannot be used, or will be of little help, you may have to resort to alterative products. What kind of products will help? Products that have antimicrobial or anti-inflammatory properties should be considered. While the absorption of asprin products in poultry is less than in mammals, we do see anti-inflammatory effects from use. Guaifenesin based products can help act as an expectorant, thinning and loosening mucous (much as it does in human use). Finally, it is important to try and reduce exposure of birds to pathogens. Proper waterline cleaning between flocks (remove built up scale and biofilm), continuous water sanitation during the flock (prevent re-formation of biofilm), proper ventilation to reduce pathogens in the air (dust/ammonia) and maintaining proper litter moisture (ensure non-optimal pathogen growing conditions) are all important for preventing and reducing severity of disease.


For More Information:


Dr. Meagan Slater, DVM, MAM, DACPV
Technical Service Veterinarian

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