[Studies on the bacterial causes of neonatal mortality in foals. Report on post-mortem findings (author's transl)].

The causes of neonatal mortality in foals were studied over a period of two years. The total number of foals studied was 121. Bacterial infection was found to be an important factor. Infection caused by A. equuli (1.6%) which previously was the most important one, has been superseded by E. coli infection (56%). E. coli infections particularly occur during the first weeks of life and, depending on the course of the disease, give rise to various pathological changes. Infections running an acute course are mainly marked by pathological changes of the lung and lymphoid organs. Infections running a subacute course are frequently associated with polyarthritis and polyserositis. Another important cause of infection during the first weeks of life is Klebsiella pneumonia (10%). The pathological changes occurring in this infection are markedly similar to those in subacute E. coli infection. Infections with Salmonella spp. (7%) mainly occur in the older foals (1-3 months) affected with polyarthritis. C. equi and streptococcal infections (11%) also mainly occur in the older foals (1-3 months). The pathological features are characterized by generalized purulent lesions in various organs. In spite of the fact that post-mortem findings suggested septicaemia, bacteriological examination was negative in 12% of the foals. The discussion is concerned with an assessment of the relationship between the pathomorphological findings and the pathogenesis of the various infections.