Pigs fed a diet supplemented with selenium >20–50 ppm for
>3 days develop a subchronic selenium toxicosis characterized by neurologic
abnormalities. Animals are initially ataxic and uncoordinated, followed by anterior
paresis, then quadriplegia. Even though neurologic impairment is occurring, the pigs
continue to eat, which would indicate neurologic damage that is not centrally
mediated. The hooves show breaks and impaired growth similar to those seen in
cattle. Alopecia may also be seen. In sows, conception rate decreases and the number
of stillborn pigs increases. Lesions of subchronic toxicosis include focal symmetric
poliomyelomalacia, which is most prominent in the cervical and thoracic spinal cord.
Death may result from complications of permanent paralysis. Hoof and hair damage is
similar to but in most cases less severe than that seen in chronic selenium
toxicosis. Treatment is similar to that for chronic toxicosis, but spinal lesions
are usually permanent.
Last full review/revision May 2014 by Jeffery O. Hall, DVM, PhD, DABVT