Cause – These diseases all fall into the infectious bacterial category.
Coryza is actually the descriptive term used to identify the thick mucus discharges usually associated with both Mycoplasmosis catarrh and Ornithosis. The bacteria (termed Chlamydia in the case of Ornithosis) lodge in the upper respiratory tract and can be extremely hard to completely eradicate. Often, infected birds never completely recover. Although their external symptoms may disappear, they can remain carriers for life.
Symptoms – The classic symptoms of respiratory infections include mucous in the throat, open beak and heavy breathing, rasping or gurgling while breathing, watery discharge from eyes, sometimes associated with swelling in the eye area. Other symptoms include discharge from the nasal area. And occasionally air sac swelling or crop swelling as torn air sacs trap air under the skin. As is usually the case with pigeons, other diseases can quickly manifest themselves when birds are in distress, so other symptoms can occur, such as loose, greenish droppings and loss of weight. Most often the only noticeable difference in our birds will be their unwillingness to fly or their complete failure in the racing events. Respiratory infections are the most damning it racing fanciers because many populations are carriers of the disease in one form or another, and symptoms are hard to identify. But results will definitely be diminished.
Prevention – The most important aspects in controlling respiratory infections are adequate ventilation without drafts, keeping dust and ammonia levels low (which means keeping droppings from accumulating) and controlling dampness and overcrowding Since tests have indicated that in some areas as much as 70% of the wild pigeon population is either infected with or carries respiratory disease, it would be wise to limit contact with feral birds. Since sporadic drug treatment at inadequate levels can cause rapid resistance to medication, always treat with effective drugs for the recommended length of time. Proper quarantining of new birds is also a must.