Chronic Respiratory Disease (CRD)
CRD is one of the most common causes of disease in backyard fowls. Chronic respiratory disease (CRD) occurs when chickens and turkeys that
are infected with Mycoplasma gallisepticum are stressed. The bacteria then
causes major damage to the bird's respiratory system.
Mycoplasma gallisepticum spreads via eggs, airborne transmission and indirect
or mechanical routes such as introducing infected birds to an existing flock,
or via bird transport containers. M. Gallisepticum can reside in a flock with
few indications of its presence until the flock or individuals in it are
stressed sufficiently to show signs of respiratory disease.
Signs of CRD
The signs of CRD are sniffling, sneezing, coughing
and other signs of respiratory distress. When suspected, observe the birds from
a distance to get a good idea of the symptoms as birds often do not display
signs of disease once caught.
Sometimes CRD slowly spreads through the flock
causing poor production, retarded growth
and wet noses. In these cases there are usually few mortalities unless the
underlying stressors increase.
Other diseases that have similar clinical signs are Coryza, Infectious bronchitis, Infectious laryngotracheitis and Fowl cholera.
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. Ask your veterinarian about appropriate treatments.
Point-of-lay pullets that are vaccinated against CRD are available from suppliers - make sure you ask about the vaccination status of the birds you are acquiring.
Management issues must be addressed before the birds arrive. Ensure birds are free of M. Gallisepticum on introduction. An all-in, all-out system with thorough cleaning down between batches and acquiring vaccinated birds helps. Ensure the nutrition and flock dynamics (size, age distribution, presence of roosters etc) are also optimal. Housing that is difficult to clean and thus accumulates manure, dust and vermin leads to many common ailments in poultry.
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