B. Listeriosis

Listerial meningo-encephalitis. This form has been observed in all species and presents a standard syndrome. In adult cattle the course of the disease is usually 1 to 2 weeks but in sheep and calves the disease is more acute, death occurring in 3 to 4 days. Basically the clinical picture combines the signs of the dummy syndrome, with pressing against fixed objects, and unilateral facial paralysis. Affected animals are dull, often at the point of somnolence, and isolate themselves from the rest of the group. Prehension and mastication are slow and the animal stands for long periods drooling saliva and with food hanging from its mouth. The affected animals become recumbent and are unable to rise. Death is due to respiratory failure. Fever (usually 104° F or 40° C, but occasionally as high as 107° F or 42° C) is usual in the early stages of the disease but the temperature is usually normal when frank clinical signs are present.

Listerial abortion. In cattle many sporadic abortions due to List, monocytogenes are recorded and outbreaks of abortion due to this organism are recorded in cattle, sheep and in goats.

Septicaemic listeriosis. Acute septicaemia due to List, mono­cytogenes is not common in adult ruminants but does occur in monogastric animals including foals, young pigs and newborn lambs and calves. There are no signs suggestive of nervous system involvement, the syndrome being a general one comprising depression, weakness, emaciation, pyrexia and diarrhoea in some cases, with hepatic necrosis and gastroenteritis at necropsy.