Some aspects of the epidemiology and control of Salmonella typhimurium infection in outwintered suckler cows.

Two outbreaks of Salmonella typhimurium infections affected outwintered, spring-calving suckler cows in late pregnancy. The infections spread rapidly both within and between groups of stock on the affected farms, with morbidity in the infected groups varying from 14.5 per cent to over 60 per cent, and mortality in adult cattle varying from 0 to 14.3 per cent. Prophylactic measures included the use of antibiotics and killed vaccines against Escherichia coli, Salmonella dublin, S typhimurium, and Pasteurella multocida. In one outbreak, use was also made of a polyvalent serovaccine and hyperimmune serum against E coli, S typhimurium, and S dublin. In both outbreaks no new cases were reported in the affected groups after the administration of the second dose of vaccine, and there was no resurgence of disease on the affected farms within 18 months of the primary outbreaks.

Septicaemia, encephalitis and abortions in a housed flock of sheep caused by Listeria monocytogenes type 1/2.

One hundred and ninety-six housed pregnant ewes were fed poor quality silage for two days. Ewes are reluctant to eat the silage and within 48 hours they became dull and developed diarrhoea and lameness. Despite treatment with antibiotics and calcium borogluconate 19 ewes died, more than 60 developed vaginal discharges and at lambing 94 ewes were barren. Six developed nervous signs and two of these died, one with lesions typical of listeric encephalitis. Post mortem lesions and the isolation of Listeria monocytogenes type 1/2 from lung, liver, spleen and kidney are described. L monocytogenes was also isolated from blood samples from live ewes. The estimated gross financial loss to the farmer was 5130 pounds or, for the flock, 26 pounds per ewe.