Dyschondroplasia is a skeletal bone disorder that occurs commonly in larger "meat-type" chicken breeds (often known as "broilers"). When it involves the tibiotarsus ('tibia') bone (the most commonly affected bone), the disorder is referred to as tibial dyschondroplasia (TD). The most common clinical sign is an abnormal gait leading to lameness.
TD involves the development of an abnormal mass of cartilage at the growth plate of the long bones (the tibia) of the leg. Instead of calcifying, the cartilage remains soft and will often bend backwards under pressure or heavy body weight. As a result, chickens with TD often suffer from spontaneous leg fractures
, necrosis, and severe pain and lameness. Birds with severe lameness are often unable to stand due to the pain. These birds will require special supportive care and will need to be relocated, otherwise they will be unable to access food or water---leading to starvation and death. If left with other birds they might also be subject to bullying from other flock members.
How Tibial Dyschondroplasia is Diagnosed
Radiographs taken of the tibiotarsus bone in birds with TD will show an abnormally large area of cartilage at the affected physis.