Further studies on “posterior paralysis” in swine

Abstract

“Posterior paralysis” is one of the terms rather loosely used to designate a trouble in swine which is characterized by stiffness, particularly in the hind legs, inability to rise or stand, the occasional swelling of the joints and fractures of the leg bones. Some preliminary studies relative to this trouble were made the subject of a previous communication. 1

In continuation of these studies, 24 pigs, around 30 pounds in weight, were placed on experiment in the summer of 1922. The characteristic symptoms were produced on a ration of yellow hominy, middlings, and casein, made into a slop with an equal weight of skim milk. A check group receiving added minerals in the form of calcium carbonate and bone meal did not develop the trouble. The alleviation of stiffness and the resumption of growth was brought about in the group receiving no extra minerals either by the addition of the minerals in question, or, by a daily addendum of 10 c.c. of cod liver oil.

In the following winter eight out of thirteen pigs developed the symptoms on the same ration, containing, however, yellow corn meal in place of hominy,—even when calcium carbonate and bone meal mere included. Orange juice was added to the ration of three of the affected pigs, which were obviously near death. There was a marked temporary improvement followed in two weeks by a decline and death. The addition of cod liver oil produced only a slight improvement over a three weeks'period. When the cod liver oil was replaced by 5 per cent. of chopped alfalfa hay in the case of two of these pigs, permanent improvement resulted.

According to the symptoms of apparent paralysis, it was thought that the lesions might be in the lumbar enlargement of the spinal cord. Examination of the cord by the Nissl's method, did not show any tissue changes. The principal and constant lesions in the pigs fed as described in the preceding paragraph were found in the bones and in the kidneys.