CRD in Poultry | Airsacculitis Treatment

Best Effective Treatment of CRD in Poultry

CRD in Poultry is always a point of debate between poultry farmers. Chronic respiratory disease (CRD), also known collectively as mycoplasma gallisepticum (MG) infection, is considered to be one of the major pathogens that cause respiratory disease in poultry.

It tends to develop slowly in flocks and is associated with progressive and chronic respiratory signs. Chickens with chronic respiratory disease often show clinical signs associated with the respiratory system, which include mild tracheitis, sinusitis, airsacculitis, and conjunctivitis.

If your birds are infected with CRD then you are in the right place. Here we will give you a complete guide on CRD in Poultry. This article will help you a lot if you are really serious about your bird’s health status. So let’s get into the detail.

What is CRD or Airsacculitis in Poultry?

Airsacculitis or CRD in Poultry is a respiratory-associated disease in poultry birds and is defined as inflammation of one or more of the air sacs. Air sacs serve as an integral part of a chicken’s respiratory system.

Chickens have nine air sacs, which are thin-walled bubble-like pockets that work as a system to circulate oxygen throughout their bodies. There are four paired air sacs (cervical, cranial and caudal thoracic, and abdominal) and one unpaired air sac (clavicular).

When a chicken’s air sacs become inflamed, it causes them to thicken and accumulate purulent, or caseous material within the air sac cavity. This leads to dyspnea or difficult breathing.

Other names: Air Sac Cold, Air Sac Infection, Air Sac Syndrome, Air Sac Disease

Cause of Chronic Respiratory Disease in Poultry:

The most common pathogens isolated from chickens with airsacculitis include Escherichia coli and Mycoplasma gallisepticum.

How is CRD Transmitted Between Birds?

M gallisepticum is transmitted vertically within some eggs (transovarial) from infected breeders to progeny, and horizontally via infectious aerosols and through contamination of feed, water, and the environment, and by human activity on fomites (shoes, equipment, etc).

Infection may be latent in some birds for days to months, but when birds are stressed horizontal transmission may occur rapidly via aerosols and the respiratory route, after which infection and clinical disease spread through the flock.

Once individuals or flocks are infected, they remain infected for life and act as carriers or reservoirs for infection. Flock-to-flock transmission occurs readily by direct or indirect contact from the movement of birds, people, or fomites from infected to susceptible flocks.

Cold weather, poor air quality or crowding, concurrent infections, and some live virus vaccinations may facilitate infection, disease, and transmission.

Epithelium of the conjunctiva, nasal passages, sinuses, and trachea are most susceptible to initial colonization and infection; however, in severe, acute disease, the infection may also involve the bronchi, air sacs, and occasionally lungs. Once infected, birds may remain carriers for life.

Symptoms of CRD in Poultry Birds:

Symptoms of CRD in Poultry Birds are

  • Eye discharge
  • Conjunctivitis
  • Gurgling sounds
  • Gaping
  • Nasal discharge
  • Facial swelling
  • Head shaking
  • Tracheal rales
  • Depression
  • Coughing
  • Difficulty breathing
  • Open-mouthed breathing
  • Tail-bobbing
  • Low exercise tolerance
Symptoms of CRD in Poultry

Open-mouthed breathing

Symptoms of CRD in Poultry


Symptoms of CRD in Poultry

Nasal Discharge

How to Diagnose CRD in Poultry Birds:

A well-renowned pathologist said,

Forget the Treatment, Diagnosis is everything

Usually, in every disease, the diagnostic protocols revolve around clinical signs and symptoms and further confirmation by laboratory tests. In the same way, to diagnose CRD in Poultry birds, you have to check the following mentioned things:

  • History
  • Clinical signs
  • Physical exam
  • Radiography
  • Auscultation of lungs and air sacs
  • Histopathy
  • Necropsy
  • Positive bacterial culture

Treatment of Airsacculitis or CRD in Poultry Birds :

Antibiotics may reduce clinical signs and vertical transmission but do not eliminate infection

Control requires good biosecurity, and prevention is typically through sourcing chicks or poults from M gallisepticum-free breeder flocks

Broad Spectrum Anibiotics:

Most strains of M gallisepticum are sensitive to a number of broad-spectrum antibiotics, including tylosin, tetracyclines, and others but not to penicillins or those that act on the cell wall.

Tylosin or tetracyclines have been commonly used to reduce egg transmission or as prophylactic treatment to prevent respiratory disease in broilers and turkeys.

Antibiotics may alleviate the clinical signs and lesions but do not eliminate an infection. Regulations on the use of antibiotics in food animals are rapidly evolving and should be consulted before use.

Name of DrugWay of Administration
Tylosin (Tylan)
Administered IM (15-30 mg/kg q6-12h), or in drinking water (50 mg/L)
Administered orally (30 mg/kg q24h) or in drinking water (100-500 mg/L) x 5 days

Tiamulin (Denagard)

25-50 mg/kg administered orally q24 x 3 days
See more at:

Administered orally (50 mg/kg q24h), or in drinking water (528 mg/L for 3-7 days)

Doxycycline (Vibramycin)

25-50 mg/kg PO q12-24h x 21 days


450 mg/kg of feed

Benefits of Probiotics:

When added to the diet of chickens infected with Mycoplasma, it alleviated lung inflammation injury caused by the infection and increased their defense against Escherichia coli by improving gut microbiota composition

Baicalin Powder

Elanco TylanVP

VetRx Veterinary Remedy

HomeoPet Cough

Healthy Gut Probiotics

UltraCruz Poultry Probiotic Supplement

Prevention and Control of CRD in Poultry:

  • Design for adequate ventilation and good air flow in chicken coop
  • Minimize stress
  • Prevent birds from getting chilled during cold weather
  • Prevent exposure to dust
  • Don’t use dusty or very fine bedding as litter for birds


CRD in Poultry is a respiratory infection in chickens, turkeys, and other avian species. Morbidity is typically high and mortality low in affected flocks, and signs are generally more severe in turkeys. Real-time PCR is becoming the most common test used for diagnosis. Antibiotics may reduce clinical signs and transmission through eggs, but they do not eliminate an infection. Control is achieved by good biosecurity and sourcing stock from M gallisepticum-free breeder flocks.

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