Saturday, April 16, 2016

Poultry Illness - Chronic Respiratory Disease

There are many potential diseases that effect poultry. Chicken keepers must always be aware of symptoms their chickens may be showing so they can determine what is wrong and find a solution quickly. Some illnesses can be spread between domestic poultry and wild bird populations. Today, we discuss the highly feared Chronic Respiratory Disease.

At a Glance

Chronic Respiratory Disease (CRD), caused by the bacteria Mycoplasma Gallistepticum (often abbreviated MG), affects the respiratory system of birds and is highly contagious. To make matters worse, there is no cure for this condition, although there are treatments to control symptoms. It is often brought into a flock by bringing in a new bird and not following proper quarantine procedures. M. Gallistepticum can be transmitted to some wild birds, making it a potential risk to wild populations. Once infected, a bird will continue to carry the bacteria for the rest of it's life, spreading it to any other bird it is in contact with.


Turkeys are susceptible to MG, making it a big problem for commercial turkey farms
M. gallisepticum is highly transmittable. It only takes coming into contact with someone who has come into contact with an infected bird, or bird's feces. The disease affects many captive species, including chickens, ducks, geese, pheasant, pigeons, and quail. Turkeys are especially susceptible to the bacteria, and infections are often more severe to them. When a bird shares a feeder or pecks the ground where someone's contaminated shoe was, it contracts the bacteria. Once that bird is infected, it spreads it to all of its flockmates, making the whole flock a carrier. CRD is transmittable through the egg, so offspring hatched from those eggs may have the illness. Chicks with CRD often die early on. Adults will likely not even show symptoms unless they are stressed, although there will likely be low hatch rate from their eggs and, as previously stated, their chicks may die quickly after hatching. All infected birds are carriers for life, and will transmit the bacteria to any bird they are in contact with. Humans can not be infected with M. gallisepticum. 

Symptoms and diagnoses 

The most common symptoms of CRD include wheezing, sneezing, coughing, decrease in egg laying, nasal discharge, and sometimes swelling of the face. There are many other diseases that cause these symptoms, so it is advisable to have your flock tested for M. gallistepticum before you make any decisions. If a bird dies, save it in the refrigerator and contact your local Department of Agriculture to see if they offer testing for common diseases. If they do not, call your nearest avian veterinarian and see if they can test the bird. A test must take place to identify MG specifically, as many other respiratory diseases follow the same symptoms. If it is positive, then you will have some tough decisions to make. 

Treatment and Options

The M. gallistepticum bacteria is resistant to penicillins, which affect the cell wall of the bacteria. They are susceptible to some broad-spectrum antibiotics, such as tetracyclines and tylosin. Treatment with antibiotics, given when there is a flair, will control the symptoms, but is not a cure for CRD. This can become costly over time. Do not sell or give away any eggs during the withdrawal period of antibiotics. Some people are allergic to certain antibiotics, and residues are left in the eggs while and after the birds are being treated. It can vary from seven to twenty-one days, and they package of your antibiotics should have it in the instructions.
Because infected bird will be a carrier for the rest of their lives, regardless of treatment, it is a wise decision to cull an entire infected flock and start over with new birds. While this sounds harsh, it is a reality. Your flock, as much as you love them, could pose a risk to native wildlife simply by being there. Not only that, but you can never sell a bird or hatching eggs, and any bird you add will also be infected with the bacteria. If your chickens are also you business, it will not be able to operate effectively when infected with this disease.

Most songbirds are resistant to MG, but it can be a big problem for Finches and other birds!
 If you choose to keep an MG positive flock and do periodic treatment, it is imperative that you have strict safety precautions, making sure that absolutely no wild birds can come in contact with your flock or their bodily fluids. If that means double-fencing or keeping your coop surrounded by a huge screen, so be it. If you go to friends house or to a feed store, make sure you're wearing shoes and clothes that have not come into contact with your chickens, and shower before going. Do not allow an MG positive flock to free range! It is your responsibility to make sure the illness doesn't leave your flock. 


CRD is prevented by basic biosecurity measures. If you visit another farm, you should shower and change your clothes and shoes before coming into contact with your flock. Any new birds should be quarantined for at least two weeks, preferably four, to see if the stress of moving brings out symptoms. Quarantined birds should be totally away from the flock, and you should change your shoes (or wear shoe covers) and clothes after you come into contact with the new bird, before caring for your healthy flock. If you take a bird to a show, also quarantine them before adding them back to the flock. They may have come into contact with the bacteria from other birds at the show. Obtaining chicks and chickens from NPIP certified breeders and hatcheries is also a good way to prevent your flock from becoming infected, as NPIP tests regularly for disease. 

Quick Recap

Chronic Respiratory Disease/ Mycoplasma Gallisepticum:
  • is extremely contagious.
  • is a permanent condition; all infected birds are carriers for life.
  • can be a threat to native avian populations.
  • is NOT transmittable to humans.
  • has symptoms treatable with certain antibiotics.
  • is a particularly menacing threat to turkeys and finches.
  • needs a test to confirm diagnoses.
  • is preventable through basic bio-security procedures.
  • is tested for in NPIP certified flocks.

Have you ever dealt with CRD? Do you think your flock may be infected? Leave a comment, ask a question! Remember to check out or Facebook page and our Instagram for regular updates!


Ley, David H., DVM, PhD. "Mycoplasma Gallisepticum Infection in Poultry."Merck Veterinary Manual. Merck Sharp & Dohme Corp, Sept. 2013. Web. 16 Apr. 2016. <>.

"Mycoplasma Gallisepticum Infection, M.g., Chronic Respiratory Disease - Chickens." The Poultry Site. The PoultrySite, n.d. Web. 16 Apr. 2016. <>.