Common Respiratory Diseases

Chickens that died from Avian Influenza

Respiratory Diseases of Chickens

Many of the illnesses that afflict backyard chicken flocks are respiratory in nature. This means they can affect the lungs air sacs (alveoli), the air ways (bronchial tubes), and windpipe (trachea).

This in turn leads to labored breathing (respiratory distress) for the infected bird.

These respiratory diseases can spread rapidly through your flock and in some cases lead to death.

For these reasons, it’s a good idea to be aware of the signs, symptoms, preventative measures, and any treatment options available so you can take the necessary precautions to help protect your flock and minimize the risk of transmission throughout the flock.


Avian Influenza (Flu)

Avian Influenza (AI), also known as the fowl plague can occur in many types of birds besides chickens.

Spreading the Disease

This respiratory disease can be highly contagious and be spread extremely quickly through your flock by rats, mice, insects, contaminated surfaces, equipment, clothing, shoes, and improper disposal of chicken manure. 

Signs & Symptoms

Respiratory distress, Loss of energy, Loss of appetite, Diarrhea, Noticeable decrease in egg production, Dark red and/or white spots on the legs and/or comb, Bloody discharge around the nose 


There is no guaranteed treatment that will just make AI go away. Symptoms may be treated with broad spectrum antibiotics. Other than that, you’ll want to separate and quarantine any infected chicken(s) away from the rest of the flock.

Make sure that they and the rest of the flock always have fresh food and water and watch your flock closely for any signs of the disease spreading. 


There is a vaccine available for AI although it requires that you apply for a special permit in order to get the vaccine. The best strategy is to be sure that you’re practicing good maintenance habits by keeping a clean, healthy environment for your flock.

Infectious Bronchitis

Infectious Bronchitis (IB) is also known as simply “bronchitis” or a “cold”. It is a very common respiratory disease among flocks and is specific only to chickens among the different types of poultry.

Spreading the Disease

Bronchitis is a highly contagious viral disease that can be spread by contact with other infected chickens, contaminated tools, equipment, surfaces, clothing, shoes, etc. It can also be spread through the air (airborne).

Signs & Symptoms

Noticeable decline in egg production, Noticeable decline in food and water intake, A chirping sound not normally heard, Noticeable watery discharge from the eyes, Coughing, Sneezing, Respiratory distress 


Antibiotics may be given to fight off associated bacterial infections. Also raising the temperature by about 5° F for laying and broody hens may be beneficial. 


Vaccines are available for IB. Check with your local vet for availability and pricing.


Pox is also known as chicken pox (no, not the same as the human type.), Fowl pox, Bird pox, Avian pox, and Avian diphtheria. This is a common disease affecting most poultry types as well as chickens and can occur at any age. 

Spreading the disease

The disease is most commonly spread by mosquitoes and contact with other infected chickens although it may also be spread by contact with a contaminated surface. It can enter the blood stream through mosquito bites, open wounds and sores and through the eyes. 

Signs & Symptoms

Wart like lesions appearing in areas that don’t have feathers like the legs and head, Noticeable decrease or cessation in egg production, Open sores and/or lesions in the mouth and/or trachea, Congestion due to inflammation of the airways, Respiratory distress 


There is no specific treatment regimen. The disease spreads fairly slowly and most birds survive with minimal or no complications. Focus on good flock maintenance. 


Vaccination is available and can be used to prevent as well as stop an outbreak although it isn’t recommended unless circumstances exist like a high mosquito population or an outbreak is already occurring.


Infectious Coryza

Infectious Coryza (IC) is also known as Coryza, Croup, and Cold. It is extremely common among chicken flocks.


Spreading the Disease

The disease can be spread by contact with infected or previously infected birds, through airborne methods like mucous spray and contaminated surfaces like coops, waterers and feeders.

Signs & Symptoms

Possible decrease in egg production, Noticeable “foul” smell from infected bird, Sticky, thick discharge from nostrils and eyes, Possible bouts of diarrhea, Eyes irritated with eyelids possibly sticking shut, Respiratory distress with associated “rattling” sound (AKA crackles or rales) 


Antibacterial meds can be given as can water soluble antibiotics to treat the symptoms of the disease although once the bird is infected; they will remain a carrier for life.

For this reason, some flock owners may choose to cull these birds from their flock. 


Vaccines are available although there seems to be some disagreement as to their effectiveness. Check with your local vet for availability and pricing.

The best method of prevention appears to be good flock maintenance and proper sanitation methods.


Mycoplasmas / Mycoplasmosis

There are two primary types of Mycoplasma disease that affect chickens. Mycoplasma Synoviae (AKA Mycoplasma S and MS)

And Mycoplasma Gallisepticu (AKA Mycoplasma G, MG, Mycoplasmosis, Infectious sinusitis, Chronic Respiratory Disease, and CRD)

Mycoplasma G is the more common among chickens although both forms can affect different types of poultry.

Spreading the disease

MG can be spread by infected wild birds, infected members of the flock, contaminated equipment as well as from the laying hen to the chick through the egg. MG in the embryo can cause dwarfism and even death. 

Signs & symptoms

Mature chickens infected with MG may exhibit no outward signs of the disease, Possible sticky, foamy nasal discharge, Possible sticky, foamy discharge from the eyes, Sinuses may become swollen and infected, Infected birds may exhibit a “rattling” sound when breathing, Sneezing may occur, Weakness, Decrease in egg production 


Antibiotics are an effective treatment. There are multiple routes they can be given. They can be mixed with feed, water or given by injection. Infected birds remain carriers for life.


Vaccines are available, but may not be suitable for small flocks. Contact your local vet for availability and pricing.

Respiratory diseases are common in backyard chicken flocks, but many of these diseases can be controlled, minimized and even prevented through vaccinations, good flock maintenance habits and taking action when you see signs & symptoms of illnesses.

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