If one of your chicken residents is struggling to breathe, this is a health emergency. Signs of respiratory distress include gasping and cyanosis (dark purple or black a fleshy crest on the head of the domestic chicken and other domesticated birds and wattles). The chicken’s breathing will likely be audible- wet, gurgly, raspy, or sound like a whistle. A bird in respiratory distress will likely remain down and be inactive.
If you have an oxygen tank and are trained to use it, you should start oxygen therapy immediately. Handle the individual as little as possible to avoid causing further stress. If you suspect the chicken has something lodged in their throat, you can look in their mouth, but be careful not to push something deeper into their throat, and be aware that the simple act of looking in their mouth will cause stress that could exacerbate the issue. You will need to weigh the risks and benefits of further handling.
Contact your veterinarian immediately. Unfortunately, the stress of transport may make matters worse, but if you have no way to handle the situation on site, you may need to take the risk. If you are able to administer oxygen, your veterinarian may advise you to wait until the bird is more stable before transporting them. The use of terbutaline, a bronchodilator, can be helpful depending on the underlying cause.