This syndrome, one of the more common congenital defects of calves, is characterized by rigid fixation of the limbs in abnormal postures; it often produces dystocia.
Affected animals may have other anomalies, including hydrocephalus, palatoschisis, and spinal dysraphism. The condition may be lethal, but some mildly affected animals recover completely. The muscle lesions may be primary in some types of the disease, but the neural lesions generally are primary, and the muscular alterations represent denervation atrophy. Congenital articular rigidity is seen in cattle, sheep, horses, and pigs.
Numerous etiologic factors have been recognized. In cattle, these include viral (Akabane virus [ Akabane Virus Infection], bluetongue virus [ Bluetongue] and plant ( Lupinus sp [ Mycotoxic Lupinosis ]) teratogens, and a heritable recessive trait in Charolais. In sheep, plant (locoweed) and viral (Akabane, Wesselsbron teratogens, Rift Valley fever, parbendazole exposure, and inherited autosomal recessive primary myopathies of Merino and Welsh Mountain lambs may cause congenital articular rigidity. In pigs, the condition may be inherited as an autosomal recessive, or result from deficiency of vitamin A or manganese or from exposure of pregnant sows to plant toxins (eg, tobacco, thornapple, hemlock, and black cherry).