A feather cyst causing vertebral bone lysis and spinal cord compression in a Lohmann Brown layer.

A feather cyst in the cervical region which, through complications of inward growth, resulted in compression of the cervical spinal cord of a Lohmann Brown layer is described. It is postulated that expansion of the cyst exerted pressure on the adjacent cervical vertebra and through bone lysis created an opening through which the cyst protruded, thereby exerting pressure on the spinal cord. The affected spinal cord segment was reduced to a fifth of its normal diameter. The bird most likely died of starvation because of limb and neck paralysis and disorientation. Although the cause of the feather cyst was not conclusively identified, moulting and trauma could have triggered its formation and subsequent growth.