One of the most common and frustrating health issues in backyard poultry is respiratory disease. There are a number of potential reasons for such a high prevalence of respiratory disease in backyard holdings:
* Many holdings have multiple ages of birds
* Many holdings have several poultry species
* Birds are regularly bought in from multiple sources (such as markets) with little or no history
* Very few backyard keepers vaccinate for respiratory disease
* Many of these birds are free range and as such come into regular contact with wild birds
Before discussing the common respiratory diseases of backyard chickens it is worth discussing the unique physiology and anatomical features the avian respiratory system.