Khan M A, Olson N O, Overman D O
Poult Sci. 1977 Mar;56(2):689-97. doi: 10.3382/ps.0560689.
The incidence of spontaneous avian spondylopathy was maintained between 58 and 66% in the progeny of one flock (Flock A) and less than 40% in the progeny of another (Flock B), by proper selection and breeding for 4 generations. Spondylolisthesis, the major type of spondylopathy present, was observed at the first and sixth vertebral levels. Spondylolisthesis was progressive in nature and consisted of a ventrodorsal rotation of the 1st and/or 6th thoracic vertebrae leading to spinal cord injury and paraplegia or partial crippling in some birds. There was occasionally extensive muscle degeneration and connective tissue proliferation around the distorted vertebrae and the spinous ligaments bridging the defect were stretched and appeared heavier than normal. Spondylopathy was also observed in 20-day chick embryos. Spondylolisthesis was observed in 33% of the embryos examined from Flock A-G2 and the other conditions present consisted of scoliosis and abnormal lordosis and kyphosis. Using a grading scale of +1 (mild) to +3 (severe), all cases of embryonic spondylopathy were graded as +1. The back defects present in Flock B-G2 embryos were entirely due to abnormal kyphosis.
通过连续四代的适当选育，一个鸡群（鸡群A）后代的自发性禽脊柱病发病率维持在58%至66%之间，而另一个鸡群（鸡群B）后代的发病率则低于40%。观察到的脊柱病主要类型是椎体滑脱，发生在第一和第六椎体水平。椎体滑脱本质上是进行性的，表现为第一和/或第六胸椎椎体腹背向旋转，导致脊髓损伤，部分禽类出现截瘫或局部跛行。偶尔会出现椎体周围广泛的肌肉退化和结缔组织增生，连接缺损部位的棘间韧带被拉伸，看起来比正常情况更厚。在20日龄的鸡胚胎中也观察到了脊柱病。在来自鸡群A-G2的33%的胚胎中观察到椎体滑脱，其他情况包括脊柱侧凸以及异常的脊柱前凸和后凸。使用从+1（轻度）到+3（重度）的分级标准，所有胚胎脊柱病病例均被评为+1级。鸡群B-G2胚胎中出现的背部缺陷完全是由于异常的脊柱后凸所致。
