May 20, 2010

Spondylitis, caused by the bacterium Enterococcus cecorum, emerges as a new disease among US broiler breeders.

The disease used to be a problem only in male broiler breeders. But recently, it has also been seen in other flocks of broiler chickens, with many birds in the flock described as having leg problems.

In broiler flocks, the problem begins between 30 and 40 days of age, often with a high morbidity rate resulting in culling of many birds in the flock. Almost all of the affected birds are males. Selective loss of males from the flock results in lowered average carcass weights at processing, and increased feed conversion rates.

Birds presented to the Animal Disease Diagnostic Laboratory showed clinical signs of leg paralysis. Typically, they were in ventral recumbency with their legs extended forward and spread laterally, and their feet slightly raised off the ground. Other birds were in ventral recumbency with their legs extended backward or severely spread to the sides.

Necropsy examination of affected birds revealed a large, firm swelling in the ventral surface of the spine at the level of the articulating thoracic vertebra. Longitudinal section through the vertebral column revealed a cavity filled with necrotic debris in the body of the affected vertebrae. Due to the damage, the vertebra became deformed and compressed the spinal cord, and this was the cause of the leg weakness and paralysis.