Pecking and Cannibalism is a term used to describe one of the most common causes of chicken diseases in many flocks, according to HobbyFarms.com. Farmers may observe the pecking directly or see the wounds, which are often located near an adult chicken's head or vent, or on the feet of chicks. Rickets, lice and infectious bronchitis are other common diseases.
In severe cases of rickets, chickens cannot walk and have deformed bones, explains HobbyFarms.com. Early symptoms include abnormally slow growth and stiff, awkward movement. Slow or no growth can also be a symptom of vitamin A deficiency, along with a crusty or cheese-like discharge in the eyes and nostrils.
The first symptoms of lice in chickens may be irritation, restlessness and frequent scratching or pecking at themselves, notes HobbyFarms.com. If it continues, the affected chickens may lose weight and stop laying eggs.
Chickens can also get infectious bronchitis, according to Local Harvest. Sick chickens may stop eating or drinking and develop a runny nose and eyes. Their breathing sounds labored and raspy, and they mostly stop laying eggs. Avian influenza has similar symptoms, but the bird may also develop red or white spots on its legs and have diarrhea. Birds with influenza may have some blood in the discharge from their eyes and nose.
Intestinal parasites are another risk, according to HobbyFarms.com. The symptoms vary depending on the type of parasite and the stage of infection, but they often include weight loss, diarrhea and other digestive problems.