Chicken Respiratory Diseases

Bacterial Infections

• A. Janmaat, a Senior Veterinary Pathologist, and R. Morton, a Regional Veterinary Officer from Darwin, Australia are both writers for Agnote. They indicate that chronic respiratory disease is caused by a bacterium called Mycoplasma gallisepticum. Its symptoms are a reduction in egg laying among breeder hens, as well as sneezing and breathing difficulties. Another bacterium associated with respiratory infection in chickens is Mycoplasma synoviae, which can lead to bronchitis. Both of these diseases can be treated with antibiotics.

  Avian coryza is caused by the bacterium Haemophilus paragallinarum. It affects older more often than younger chickens. This disease is not transferrable to the eggs, but it can limit the number of eggs produced by females. The symptoms are swelling in the face, difficulty breathing, a loss of appetite, and runny discharge from the nostrils. Infected chickens may also shed their feathers, or molt. The disease can lead to secondary streptococcus and staphylococcus infections. The infection can be treated with the antibiotic erythromycin, according to the University of Maine.

Viral Infections

• The Poultry Site Quick Disease guide explains that infectious bronchitis is caused by a coronavirus. The symptoms are coughing and sneezing. The egg quality in breeder hens will suffer because the eggs may have either soft or rough shells, or the hens may stop laying. The treatment for infectious bronchitis is sodium salicylate. It can be prevented through vaccination.

  The respiratory adenovirus infection, or mild respiratory disease, does not usually cause death among chickens. The disease is characterized by a mild cough. There is no treatment available, but quarantining sick chickens and providing good sanitation usually can prevent the infection from spreading.

  ILT, or infectious laryngotracheitis, can cause high mortality rates among poultry flocks. The disease is seen most commonly in adult birds. Severely affected chickens may have difficulty breathing or may cough up bloody mucus. There is no treatment for ILT after onset of the disease, but it can be prevented through the use of vaccinations, according to Janmaat and Morton.

Fungal Infections

• Aspergillosis is a fungal infection that is caused by Aspergillis fumigatus. It has a higher mortality rate among young birds than among older poultry. The symptoms are loss of appetite, lethargy, difficulty breathing and discharge from the eyes. The disease eventually causes pneumonia and death. There is no treatment for aspergillosis. Janmaat and Morton recommend killing infected chickens and burning their carcasses to prevent the disease from spreading to the rest of the flock. The disease can be prevented by keeping their housing area clean of droppings and by using a high quality feed, according to The Poultry Site.