Exotic Diseases

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For more information and useful sites please check the Bovine Spongiform Encephalopathy page in the VEIN Links section.

Species Infected

recently described in cattle, similar disease in zoo ruminants

evidence that some Felidae may also be infected

Clinical Signs

• incubation and duration not completely known
• initial signs are subtle changes in behaviour suggestive of hypomagnesaemia
• apprehension or fear
• reluctance to go through gates or enter dairy
• aggressive behaviour
• hyperaesthesia to both auditory and tactile stimuli
• normal handling may evoke kicking
• excessive grooming/licking especially flank and nose
• abnormalities in gait and posture will become increasingly apparent
• hind limb ataxia characterised by a shortened stride and swinging gait
• difficulty in turning
• ataxia may eventually involve forelimbs, or develop into paresis with stumbling and recumbency
• tremors of head and neck may be seen
• reduced milk production, loss of weight and condition

Lesions

• histopathological only: bilaterally symmetrical spongiform change apparent as neuronal vacuolation

Pathogenesis

• unknown

Aetiology

• infectious agent thought by most to be similar if not identical to the scrapie agent of sheep
• only one strain identified

Epidemiology

• reported first in British Isles, Oman, now in some other European countries and Japan
• suggestion that cattle were infected by meatmeal derived from scrapie - infected sheep offal not effectively sterilised by rendering
• no firm evidence as yet of cattle to cattle, or parent to offspring transmission
• evidence firming of a link to variant Cruetzfeldt-Jakob disease in humans

Differential Diagnoses

     1.  hypomagnesaemia
     2.  nervous ketosis
     3.  other bovine encepahalidites (lead poisoning, listeriosis, rabies)