Respiratory tract infections occur commonly in birds and can affect the upper or lower respiratory tract. Infections can be caused by a virus, bacteria, parasites, or fungal agents. The type and severity of the infection depends on the cause, the length of time of the infection, and the immune status of the bird. The most common organisms known for causing respiratory infections in chickens include:
- Mycoplasma gallisepticum: This is a very common bacterial organism found worldwide. Infection with this bacteria can cause respiratory disease if the chicken is exposed to a stressful event, resulting in the onset of Chronic Respiratory Disease.
- Chlamydophila psittaci: This is a zoonotic, Gram-negative bacterial organism which is commonly found around exotic pet birds. Infection with this bacteria has been associated with respiratory disease in chickens, which is referred to as Avian chlamydiosis.
- Pasteurella multocida: This is an organism most commonly transmitted through predator attacks, which can result in the onset of Fowl Cholera.
- Ornithobacterium rhinotracheale: This is a Gram-negative bacterium known for causing respiratory infections in avian species worldwide. Infection with this bacteria is referred to as Ornithobacteriosis.
- Avibacterium paragallinarum: Previously referred to as Haemophilus paragallinarum, infection with this organism can cause Infectious Coryza, a disease which primarily affects the chicken's upper respiratory tract, specifically the nasal passages and sinuses.
- Cryptosporidium: This is a coccidian protozoa parasite which has been associated with causing respiratory, urinary tract, and/or gastrointestinal disease in infected birds. Infection with this organism is referred to as Cryptosporidiosis.
- Infectious bronchitis virus (IBV): This is a type of coronavirus which is fast acting and highly infectious--meaning the entire flock will be infected within 24-48 hours upon exposure. The resulting disease associated with infection with this virus is referred to as Infectious Bronchitis.
- Laryngotracheitis virus (LTV): Also known as the Gallid herpesvirus 1, this highly contagious herpesvirus is responsible for causing outbreaks of Infectious Laryngotracheitis.
Respiratory Infection Signs
Clinical signs observed in chickens differ depending on whether the infection occurs in the upper respiratory tract or the lower respiratory tract. The stage and severity are also significant factors influencing the symptoms displayed by affected birds. Observe the chicken from a distance to evaluate any subtle changes in their posture, respiratory rate, respiratory pattern, or wing position that may indicate an abnormality. Normal respiratory effort in chickens shouldn't be noticeable, and their mouth should be closed.
Signs associated with the Upper Respiratory Tract
Signs associated with the Lower Respiratory Tract
- Facial swelling
- Discharge and/or blockage of nares
- Open-mouth breathing
- Exercise intolerance: the bird tires quickly with minimal exercise.
- Eye discharge or watery eyes
- Stretching neck outward
- Change in voice
- Exercise intolerance
- Abnormal respiratory sounds, such as crackling,'honking', or rales.
- Loss of voice
- Change in vocalization
- Labored respiration
- Tail-bobbing (rhythmic jerking of the tail)