Thursday, May 3, 2012
Last month Victoria focused on two respiratory conditions that can be devastating to chickens. But there are others to watch out for too …
Blocked nasal openings
This can obviously be a problem with chronic respiratory problems. Discharge accumulates and hardens at the nasal opening but it is possible to soak and remove this carefully from a conscious bird, remembering that some species have a sensitive operculum (nostril cover), which needs to remain in place.
All classes of poultry are susceptible. It is a very difficult disease to treat successfully as there are few early symptoms and once it spreads throughout the air sacs, lungs, hollow bones and abdomen it is probably too late. Mouldy hay or straw or rotting or decaying vegetable matter, such as bark, should be avoided as a substrate, as it is the spores of the fungus that are inhaled; wood chips do not support the fungus. Most healthy unstressed birds will cope with a low level of infection, but birds under stress may die suddenly. It is also passed to the chick through the egg. This disease is zoonotic, causing Farmer’s Lung in humans.
Antifungal agents such as itraconazole are successful if the disease is caught early enough, or the affected bird can be nebulized with F10, a recent disinfectant which is non-toxic to the birds.
This is a general term covering several air sac diseases in all poultry ranging from parasitic (air sac mites: mainly a problem in very small adult birds) to chlamydophilosis to aspergillosis.
Air sac leakage: subcutaneous emphysema sometimes occurs, usually the cervical air sac leaks and air appears under the skin locally or all over, making the bird look like a balloon caricature. If this does not resolve in a few days, a nick can be made in the skin to let the air out. This small amount of skin can then be sutured open which aids the air sac to heal by slow metabolism.
Infectious Bronchitis (IB)
This is a coronavirus causing respiratory disease and kidney damage in young poultry, plus oviduct infection with depressed egg production and poor shell quality (often wrinkled) in layers. Birds laying the odd wrinkled egg may be carriers and should be culled. Poor shaped eggs should not be set for hatching. The signs of IB are similar to mycoplasma and the spread of infection is 1-3 days throughout a flock: mycoplasma tends to have lower morbidity (affected birds). Commercial flocks vaccinate against IB and ND with a combined vaccine and pet bird owners may opt to do the same if there is a problem in the area. However, vaccination has not proved to give particularly good control in outdoor birds. Because the presence of mycoplasma predisposes birds to IB, it is very important to control the incidence of mycoplasma in the flock (see Mycoplasma article).
A commensal (normal inhabitant) in many mammals but not generally in poultry or wild birds. Rats are a known infective source. The disease is known as fowl cholera and symptoms include respiratory distress, lameness, lethargy and swollen wattles. Antibiotics and sulphonamides are effective and there is also a vaccine.
Chlamydophila psittaci, known as psittacosis in parrots or ornithosis in other birds, is a potentially dangerous zoonotic disease as it may cause pneumonia and abortion in humans.
Bird keepers need to inform their doctors of their hobby so that in event of illness this disease may be part of the differential diagnosis.
Infection in birds can cause ocular and nasal discharge and distressed breathing. It is confirmed by laboratory (ELISA) test. There is a misconception that it can only be caught from parrots, but turkeys, ducks, pigeons and sheep have also been implicated. It is no longer advised to treat it as it has, as part of its life cycle, a stage that hides inside cells, and although long term antibacterials can reduce the symptoms, as soon as these are stopped, the diseases re-appears.
Infectious Laryngotracheitis (ILT)
This is caused by a herpesvirus and mainly affects male, heavy breed chickens and turkeys. Symptoms are a nasal discharge, gasping and tracheal plugs of mucus which can cause death. Mycoplasma, IB, Vitamin A deficiency and ammonia will predispose to more severe disease plus there is a carrier state. There is a vaccine.
The economic impact
A notifiable disease outbreak can cause loss of entire flocks whether through death or culling and any compensation is based on commercial values – pure breeds are only valued as if they were commercial layers or meat birds.
Lesser respiratory problems can at least cause loss of production plus poor welfare for the birds.