HISTOPATHOLOGICAL CHANGES IN THE COELIACO-MESENTERIC GANGLIA OF HORSES WITH MAL SECO, A GRASS SICKNESS-LIKE SYNDROME, IN ARGENTINA

'Mal seco' is a grass sickness-like syndrome of horses in Argentina. A histopathological study was made of the coeliacomesenteric ganglia of four horses with 'mal seco' and of four horses that died from other c auses. The severity and extent of the lesions found in the horses with 'mal seco' was greatest in the two with the shortest clinical course. Degenerative changes consisted mainly in the loss of Nissl substance, cytoplasmic vacuoles, neuronophagia, intercellular and intracytoplasm ic eosinophilic bodies, and pyknotic and eccentric nuclei. The coeliac o-mesenteric ganglia of the control horses had no histological lesions . The histological lesions in the horses with 'mal seco' were very sim ilar to those described in the coeliaco-mesenteric ganglia of horses w ith grass sickness in Europe and it is suggested that 'mal seco' and g rass sickness may be the same disease.