Focal symmetrical encephalomalacia in swine from ingestion of Aeschynomene indica seeds.

Abstract

A spontaneous outbreak of neurological disease in swine caused by the ingestion of Aeschynomene indica seeds and reproduction of the disease in the same specie are reported. In the natural outbreak the morbidity, mortality and lethality rates were respectively 25%-40%, 8.5%-20%, and 25%-66%. Clinical signs were variable degrees of incoordination of gait, falls, sternal recumbency with wide base stance of the hind limbs, lateral recumbency and death. For experimental reproduction of the intoxication, 5 (A-E) pigs were fed a ration containing 10% (PigA), 15% (Pig B) and 20% (Pigs C-E) of A. indica seeds. Pigs A and B were euthanatized and Pigs C-E died of acute disease respectively 16, 21 and 24 hours after the start of the experiment. Clinical signs were similar to those observed in pigs from the spontaneous outbreak. Histopathological findings in the brain of pigs fed rations with 20% A. indica seeds (C-E) were congestion, edema and hemorrhage and swollen capillary endothelia in nuclei and in the telencephalic cortex. Pigs fed 10% and 15% A. indica had histopathological changes in the brain of discrete focal symmetrical areas of malacia. These findings indicate that one or more toxic principles in A. indica seeds are responsible for this neurological condition and that clinical outcome and pathological changes are dose-dependent. The symmetrical malacic foci from the ingestion of A. indica seeds in pigs affected vestibular and cerebellar nuclei, putamen, and the mesencephalic substantia nigra, oculomotor, and red nucleus; thus, focal symmetrical encephalomalacia is suggested as a better name for the disease.