Chickens: Chronic Respiratory Disease (CRD)

Chicken Respiratory Disease (CRD)

What is Chronic Respiratory Disease in Chickens?

CRD is one of the most common causes of disease in backyard hens seen at the chicken vet.

Classic Chronic respiratory disease (CRD) occurs when chickens and turkeys that are infected with Mycoplasma gallisepticum are stressed. The bacteria then causes Respiratory disease.

Mycoplasma gallisepticum is contagious and can spread through a flock. The symptoms and disease will depend on the birds vaccination status and immunity.

Signs of Respiratory Disease as seen by Melbourne Chicken Vet

The signs of CRD see at the Poultry vet in Burwood are

Sneezing, coughing , weepy eyes, gurgling, wheezing and other signs of respiratory distress.

More advanced cases have nostrils blocked with mucus or dried “pus” , as well as pus build up in the sinus and oral cavity.

Similar Diseases Seen At Bird Vet Melbourne

Other diseases that have similar clinical signs are Coryza, Infectious bronchitis, Infectious laryngotracheitis and Fowl cholera.

Medications for Chickens with CRD

There are antibiotics that can help to control the disease but reducing stress is an essential component to managing the disease once it is in the flock.

  1. Doxycycline is great first choice antibiotic used by chicken vets; it is NOT registered for egg layers
  2. Lincomycin combined with Spectinomycin is the most commonly used product for treating a flock with CRD  at the chicken vet ; as there is no withholding period for eggs !
  3. Chlortetracycline another product registered for egg layers .
  4. Enrofloxacin for individual birds – off label use
  5. Tylosin

Treatment for Chickens with CRD at Bird Vet Melbourne

Nursing care for any sick patient is important, tending to the birds needs both medical, environmental.

Eye drops regularly to loosen secretions

Nose drops usually saline, or antibiotics to treat the sinus infection.

Special feeding with palatable tastly food for your sick chicken

Warmth usually around 20 degrees

Decreasae stress Separated from flock usually with one other bird

At the chicken vet we have heated chicken enclosures and a spacious out door chicken runs.

Some chicken vet believe that Chronic Respiratory Disease is due to a combination of Chlamydia, Mycoplasma and E. coli.

Prevention – Vaccination with a Mycoplasma Vaccine at hatch and treating and quarantine of new birds.

Chicken veterinarians find that respiratory infections can be divided into two main groups, viral and bacterial.

Viral Disease that play a role recognized by poultry vets include:

  • Infectious Laryngotracheitis
  • Infectious Bronchitis
  • Newcastle Disease
  • Avian Influenza.


Bacterial Disease that play a role recognized by  Poultry vets include:

  • Haemophilus
  • Pasteurella
  • Other secondary bacteria that invade infected sinuses.
Chicken Respiratory Disease


  1. Paulfils Ferdinand on April 8, 2024 at 12:40 pm

    I need many medications for for my chickens

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