Emergencies/Illness Health Issues

Respiratory Infections

An Overview

I’m hesitant to say that I haven’t had to deal with respiratory infections in my flock. The reason being, every time I post a piece admitting my lack of experience with a particular illness, shortly thereafter one of my birds presents with those symptoms as though trying to give me some experiential knowledge to assist with my writing. But knock-on-wood, so far I have been fortunate in this area.

I belong to several Facebook chicken groups and often see posts about respiratory illnesses. Advice and treatment regimes are freely given, but it’s important to understand what kind of infection and what area it’s affecting before implementing a treatment plan.

Respiratory infections can be caused by a virus, bacteria, parasites or fungus, and can affect the upper or lower respiratory tracts. The type and severity of the infection depends on the cause, the length of time of the infection, and the immune status of the bird.

Symptoms of Upper Respiratory Tract Infections:

  • Sneezing
  • Facial swelling
  • Discharge and/or blockage of nares
  • Yawning
  • Open-mouth breathing
  • Fatigue
  • Head-shaking
  • Eye discharge or watery eyes
  • Stretching neck outward
  • Change in voice

Symptoms of Lower Respiratory Tract Infections:

  • Decreased activity
  • Abnormal respiratory sounds such as crackling, honking or rales
  • Change or loss of voice
  • Coughing, sneezing
  • Labored respiration, open mouthed breathing
  • Tail-bobbing (rhythmic jerking of the tail)
  • Head-shaking
  • Facial swelling
  • Stretching neck
  • Plugged nares or discharge
  • Tearing or discharge from eyes
  • Yawning

The most common respiratory illnesses are:

Aspergillosis: fungal disease caused by Aspergillus, a common mold found throughout the environment. In chicks it is referred to as Brooder Pneumonia. Symptoms: gasping, tail bobbing, open mouth breathing, depression, decreased appetite, delayed crop emptying, blue-purple comb, weight loss and coughing.

Brooder Pneumonia
Brooder Pneumonia

Avian Influenza (AI): a highly contagious viral infection of birds that most commonly affects commercial farms; can be low or high pathogenic. Low pathogenicity avian influenza (LPAI) viruses cause mild respiratory signs and birds often recover, while highly pathogenic avian influenza (HPAI) viruses cause more severe forms (multi-systemic infections) and high mortality.

Symptoms vary from a mild infection – loss of appetite, deceased egg production, mild respiratory disease, and diarrhea – to severe respiratory, neurological, and gastrointestinal signs with high mortality rates.

Chronic Respiratory Disease (CRD): Caused by Mycoplasma gallisepticum (see below). When birds are co-infected with multiple pathogens such as E. coli, M. meleagridis, M. synoviae, Infectious Bursal Disease Virus (IBDV), and/or Newcastle Disease Virus (NDV) it often increases the severity of symptoms and makes it more difficult to diagnose.

Symptoms: may be asymptomatic until triggered by stress;  birds between 4 to 8 months of age, and male chickens are more likely to develop classic, more severe symptoms: nasal discharge; coughing; eyelid or facial swelling; conjunctivitis; watery eyes; sinusitis; conjunctivitis;  facial swelling around and just below the eyes caused by the accumulation of pus in the sinuses.

Chronic Respiratory Disease
Chronic Respiratory Disease (Credit: Bird Vet Melbourne)

Fowl Cholera (FC): usually appears as an acute, septicemic disease causing diarrhea; ruffled feathers; increased respiratory rate; depression; sudden death; and blue-purple coloured comb immediately prior to death. It can also occur as a chronic disease with a localized infection (e.g. hock or wing joints, footpad, tendon sheath, ear, sinuses, wattles). Chronic  infection in the ear results in wry neck.

Mature chickens are more susceptible than young ones, and turkeys are more susceptible than chickens. Chickens under 16 weeks of age generally are quite resistant. Complications with severe chronic sinusitis include: accumulation of mucus,  pus and cheesy necrotic debris, which becomes so bulging that the increased pressure causes damage to the nares, nasal conchae, operculum, and nasal cavity of the chicken. Chickens are at an increased risk of developing ‘sunken eye’, in which the globe of eye retreats into its socket. This gives the appearance of the chicken ‘losing it’s eye’, and usually just involves one eye, but it can occur in both eyes.

Fowl Cholera
Fowl Cholera (Credit: Cornell U.)

Infectious Bronchitis (IB): widespread rapidly spreading, highly contagious upper respiratory infection caused by a coronavirus; sometimes affects the renal and reproductive systems.

Symptoms: sneezing; gasping; coughing; nasal discharge; wet eyes; swollen sinuses; hunched chicks; decreased egg production.

Infectious Coryza (IC): Acute upper respiratory tract infection; less severe in younger birds than in adults; most often transmitted to flocks by introducing new chickens or reintroducing of existing flock member that recently attended an event which included other poultry.

Symptoms: nasal discharge; facial swelling; conjunctivitis; swollen face and wattles, particularly roosters; difficulty opening eyes due to sticky discharge; labored breathing; coughing; sneezing; loss of appetite; decreased egg production; gunky eyes; foul odor; more common in summer and fall.

Infectious Coryza
Infectious Coryza

Infectious Laryngotracheitis (ILT): Highly contagious, acute infection caused by a Herpes virus; strains vary in virulence from highly infectious and usually fatal to low virulent strains that cause mild to asymptomatic infections; usually seen in adult chickens over 14 weeks of age.

Symptoms: conjunctivitis; nasal discharge; swollen face; head shaking; bloody mucous discharge; coughing up blood.

Mycoplasma Gallisepticum (MG): Slow spreading, chronic respiratory disease in chickens. All flock members will become infected with MG; however, not all of the birds will show signs of illness; young birds 4- 8 weeks of age are at highest risk. May be co-infected with E. coli, other forms of Mycoplasma, Infectious Bursal Disease Virus (IBDV), or Newcastle Disease Virus (NDV), which increase the severity of symptoms and makes it more difficult to diagnose.

Symptoms: foamy eye discharge; conjunctivitis; mild tracheitis; airsacculitis; swollen sinuses; more common in winter; roosters usually have more severe symptoms; triggered by stress.

Newcastle Disease (VND): Highly contagious virus.

Symptoms vary depending on the system affected. Some virus strains attack the nervous system, others the respiratory or digestive system; most common signs: uncoordinated walk; stumbling; loss of balance;  abnormal head and neck position; partial or complete paralysis of legs and wings; general weakness; diarrhea; sudden death.

Swollen Head Syndrome: Acute, highly contagious upper respiratory tract infection.

Symptoms:  swelling of the sinuses, particularly around the eye; mild conjunctivitis.

Swollen Head Syndrome
Swollen Head Syndrome


  • Chicken respiratory infections are usually spread by direct contact between infected and uninfected chickens or items that infected chickens have sneezed or coughed on, such as transport coops or clothing.
  • An infected hen can transmit Mycoplasmosis through her eggs to her chicks.
  • Preventing respiratory illness from invading your flock and having a major impact is a matter of good biosecurity and flock management. Attention to biosecurity (things you do routinely to keep infectious diseases out of your flock) can help you avoid bringing respiratory infections home to your chickens.
  • If an infection should happen to get through your defenses, a heathy, stress-free and well-fed flock is less likely to experience severe disease.
  • Infected birds can recover and appear healthy, but carry and spread the disease to other chickens, possibly for the rest of their lives.
  • Vaccines are available to control several respiratory infections, including Fowl Cholera, Infectious Coryza, Mycoplasmosis, and Infectious Laryngotracheitis.

You can guess, but you won’t be able to tell for certain which disease is causing your chickens’ woes, unless you have laboratory tests performed. Veterinary diagnostic laboratories and veterinarians who treat poultry can help you.

Although diagnostic tests will cost you some money, getting to the bottom of the problem may be worth the expense, because a diagnosis allows you to provide the appropriate treatment. Antibiotics can be helpful to control the signs of some infections (i.e. bacteria), but not others (i.e. viral). The misuse of antibiotics can lead to pathogen resistance.

If you have birds die with respiratory symptoms consider sending them for a necropsy so you have a confirmed cause of death and a better understanding of potential underlying issues that might be affecting the rest of your flock.

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