CRD

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Chronic Respiratory Disease

If CRD is common in your area, you can use medicated chick starter to help them from not getting it, or vaccinate with LS-50. If you do have it, you can either allow it to run its course, and cull birds that can't get over this on their own, or treat with the medications listed below to assist them in recovering. Keep this in mind, if you decide to medicate, you may be allowing your birds to NOT develop a natural immunity. If you allow them to deal with the problem on their own, and they get better quickly, they will have some degree of natural immunity, which will make your flock stronger in the long run. Either way, birds that can't get over the symptoms that CRD produces should be culled, or at the very least, not used as brood stock.

Causes

Mycoplasma Gallisepticum Bacteria infection.


Symptoms

  • Rattle in the chest while breathing. (Sometimes the rattle doesn't show up until the birds are on the roost in the evening, and that is the best time to check for this condition.)
  • Bubbles in the eye.
  • Runny nose.
  • Coughing or sneezing.

Note: Not all symptoms need be present to have CRD. Symptoms may return from tissue damage to the lungs during stress, even after they have recovered from the initial infection.


Treatments


Prevention

Chicks that are exposed to these carrier birds may develop a natural immunity to CRD.


WARNING

Do NOT consume eggs from treated birds until at least 7 days from the end of treatments.


Additional Information

Mycoplasmosis (CRD, Air sac, Sinusitis)

Organisms in the genus Mycoplasma are a significant cause of respiratory disease in poultry. Of the numerous species of Mycoplasma that have been isolated from domestic poultry, three are of known significance. Mycoplasma gallisepticum is associated with chronic respiratory disease (CRD)/air sac syndrome in chickens and turkeys and infectious sinusitis of turkeys; Mycoplasma meleagridis is associated with airsacculitis in turkeys; and Mycoplasma synoviae is the cause of infectious synovitis in chickens and turkeys.

Chronic respiratory disease (CRD), air sac syndrome and infectious sinusitis of turkeys have a common cause. CRD was first recognized as a chronic but mild respiratory disease of adult chickens. It reduced egg production but caused little or no mortality. Afterward, a condition known as "air sac disease" became a problem in young birds. It caused high mortality in some flocks. Many birds became stunted, feed efficiency was reduced, and many fowl were rejected as unfit for human consumption when processed.

Infectious sinusitis in turkeys produces a sinus swelling under the eye as well as an inflammation of respiratory organs. It is a chronic disease adversely affecting growth and feed conversion. It may also cause significant mortality in young poults.

A peculiar bacterial-like organism known as Mycoplasma gallisepticum (MG) is common to all three conditions. CRD and sinusitis in turkeys are caused by a pure MG infections while the air sac syndrome is caused by an infection of MG in combination with E. coli. These conditions are triggered by acute respiratory infections such as Newcastle disease or infectious bronchitis.

Mycoplasma gallisepticum is widespread and affects many species of birds. Eradication programs have reduced the incidence in recent years. It is primarily spread through the egg. Infected hens transmit organisms and the chick or poult is infected when it hatches. Organisms may also be transmitted by direct contact with infected or carrier birds.

The true CRD produces slight respiratory symptoms such as coughing, sneezing and a nasal discharge. In the air sac syndrome there is an extensive involvement of the entire respiratory system. The air sacs are often cloudy and contain large amounts of exudate. Affected birds become droopy, feed consumption decreases and there is a rapid loss of body weight.

Infectious sinusitis in turkeys occurs in two forms. When the "upper" form is present, there is only a swelling of the sinus under the eye. In the "lower" form, the lungs and air sacs are involved. The air sacs become cloudy and may contain large amounts of exudate. Both forms of the disease are usually present in the flock and frequently are present in the same bird.

Diagnosis of either condition must be based on flock history, symptoms and lesions. Blood tests are useful in determining whether a flock is infected.

The answer to the MG problem in both chickens and turkeys is eradication of the disease organisms. This goal has been achieved in commercial breeding flocks with voluntary programs conducted by the National Poultry Improvement Plan (NPIP) and National Turkey Improvement Plan (NTIP). The treatment of CRD, air sac syndrome and the lower form of infectious sinusitis is not considered satisfactory. Many antibiotics have been used with varying success. Whether to give treatment is a decision that must be made on each flock based on economic factors. If treatment is attempted, give high levels of one of the broad spectrum antibiotics (Tylan, Gallimycin, Baytril) either in feed, drinking water or by injections. The "upper"; form of infectious sinusitis can be treated with success by injecting antibiotics into the swollen sinus cavity.


Sources

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