Tibial Dyschondroplasia

Tibial dyschondroplasia (TD) is a prevalent skeletal abnormality associated with rapid growth rate in many avian species. Tibial dyschondroplasia is characterized by the presence of a nonvascularized, nonmineralized lesion that extends from the epiphyseal growth plate into the metaphysis of the proximal tibiotarsal bones.

Signs

Lameness, stilted gait and swelling of the femoral tibial joints. Also bowing of the bones or a reluctance to move may also be seen.

Diagnosis

All species of young bird are susceptible to this chronic disease. The aetiology of the disease is the failure of the chondrocytes to hypertrophy (increase in size) resulting in abnormal cartilage, which cannot be invaded by blood vessels. Vascular invasion of the cartilage from the metaphysis is not adequate and/or defective chondrolysis occurs. History, clinical signs and postmortem lesions (abnormal mass of cartilage in tibial head) are characteristic. Microscopically, dyschondroplasia is characterised by persistence and accumulation of pre-hypertrophic cartilage and begins as early as the first week of age. Chondrocytes in abnormal cartilage are smaller and shrunken. It simulates perosis, rickets and osteochondrosis (necrosis of growth plate primarily in the vertebrae and femoral head).

Treatment

Changing diets, such as reducing phosphorus relative to the level of calcium, will reduce the disease. Feed a diet free of Fusarium and tetramethyl thiurams sulphate. TD is not contagious.

Prevention

Slow the growth rate and select strains with lower incidence of TD is the best prevention.