MY CHICKEN HAS A COLD...
by K. J. Theodore
They probably have one of any number of upper respiratory ailments, such as Infectious Coryza, Infectious Bronchitis, a CRD, or perhaps some other form of respiratory distress including bacterial, fungal, or viral infection. But chances are, they donít have the Common Cold.
Iím going to concentrate on one of the possibilities, INFECTIOUS CORYZA, in this column since its incidence seems to be rising in numbers amongst the Fancier flocks.
Once thought of as a problem related to a particular region of the US (the Southeast), and to California, it is now evident that there are cases everywhere as a result of buying, selling and thereby shipping, birds all over. It only takes one new infected bird to cause widespread infection in an otherwise Coryza-free flock.
Coryza (previously known as things like a cold or roup) is caused by bacteria called Heamophilus paragallinarum, which primarily attacks the upper respiratory system, including the nasal passages. Swelling of the face, wheezing, sneezing, nasal discharge, conjunctivitis (including Ďbubblesí at the corner of the eye), eyes glued shut, and open-mouth breathing are some of the more common symptoms. And they may appear singly or in various combinations. But the most telltale symptom is the unmistakable odor that is generated from the nasal discharge. Once youíve smelled this odor, youíll identify it every time. Additional symptoms unrelated to breathing can be a drop in production, reduction in fertility, diarrhea, and a decrease in water consumption. Although not as common, if rales are detected, then it is safe to assume that the lower respiratory tract is involved as well.
Coryza can be chronic in nature or acute, and youngsters tend to suffer from less severe cases than the adults. The acute cases are spread rapidly and death can occur within hours to days of the first symptoms. The incubation period is from 24 to 48 hours, which is considered relatively short. The chronic disease can last a lifetime in your flock, passing from one bird to the other until your entire flock has been exposed. Once a flock has been exposed to Coryza, survivors are considered reservoirs of infection (carriers), whether they had outward physical symptoms or not.
Coryza does not pass vertically to the egg. However, its transmission to the rest of the flock is widespread and thorough through a host of ways. One way is through contaminated drinking water. Once an infected bird drinks from a community drinking trough, it leaves behind the bacteria through its nasal discharge. Water also becomes contaminated by feces that end up in the water and also through the dust in the air that contains bacteria and settles into the water.
Another means of spreading is done through the feed source. The same rules apply here that Iíve mentioned about the drinking water.
Simple contact with other birds and the aerosol droplets of bacteria in the air caused by infected birds are also a common means of transmission of the disease.
You should not vaccinate against Coryza unless you know you already have it in your flock. Treatment is somewhat effective in chronic cases using a host of easily obtainable antibiotics. Erythromycin and oxytetracycline (Terramycin) are two listed in Veterinary texts. However, Coryza is also becoming somewhat resistant to some of these drugs and reinfection sometimes occurs after treatment is stopped. I understand that Baytril (enrofloxicin) is very effective against Coryza, but as most of you know, is difficult to get and expensive. However, if you build a good working relationship with your local Vet, he may be a source for the drug. Also, some poultry supply houses do sell the water-soluble liquid for poultry, if you look around.
Iíd like to make a note here about injectables. It is my belief that in general, water-soluble antibiotics used to treat the drinking water are usually not as effective. The reason for this is because (especially in the case of Coryza), sick birds are usually off of feed and water anyway, and theyíre the ones who need it the most. If you just canít bear the thought of an injection, then consider using the drenching method to medicate. This would involve squirting the proper dose of medication right down the birdís throat using a syringe without a needle.
H. paragallinarum (the Coryza-causing bacteria) is fragile and easily destroyed by disinfection. Prevention of the disease is relatively safe and easy with the use of a disinfectant such as Oxine. Fogging the coop on a routine preventive maintenance schedule and treating the community drinking water with 7 drops of Oxine per gallon of water would help discourage the incidence and spread of Coryza. (Oxine is EPA approved for the use in the drinking water of all poultry and livestock.) Although not mentioned often, I have found some reference to the possibility of air-borne introduction of the bacterium into the environment.
Unfortunately, many times in a case of Coryza, there exists a secondary issue of M. gallisepticum (MG), which can affect the outcome of recovery. Baytril is now being thought of in some circles as a virtual miracle cure for MG, and therefore, my treatment of choice. In theory, it would effectively eliminate both problems simultaneously.
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