Lesion profiles and gliosis in the brainstem of 135 Swiss cows with bovine spongiform encephalopathy (BSE).

Lesion profiles are considered to be an important tool for the comparison of the various animal and human spongiform encephalopathies and to obtain information upon prion strain variations. Histological and immunohistochemical reactions (PrPsc, GFAP) in 13 brain areas at 4 levels in the brainstem from 135 BSE-positive and 45 BSE-negative cases were retrospectively evaluated. In this retrospective study a lesion profile based on histological features was worked out on the basis of BSE cases originating from Switzerland over a period of ten years. They were confirmed post mortem by histology and immunohistology. Our findings were reviewed in comparison with lesion profiles published in England. No striking differences comparing type and quality of lesions in the relevant areas between the Swiss and the English cases were evident. Moreover, the lesion profiles and the character of the lesions did not differ between animals born before or after the offal feeding ban, which supports the hypothesis that the Swiss epidemic is sustained by the same single, stable strain of the BSE agent, which is probably the same as in the English epidemic. There was a good correlation between PrPsc accumulation and spongiform changes, in particular in those areas which were morphologically most affected. Astrocytosis in BSE was quantified. A significant rise in GFAP-positive cells could be shown comparing the brain stem nuclei of BSE affected with BSE-unaffected cattle, despite considerable variation between the cases and between the nuclei. The observed astrocytosis did correlate with vacuolation of the neuropil and of perikarya as well as with PrPsc accumulation.

Decreased sedation by xylazine and high blood pressure in cows with BSE.

Fifteen cows with bovine spongiform encephalopathy (BSE) and 90 healthy cows were given xylazine intramuscularly at a dosage of 0.15 mg/kg bodyweight. The onset of sedation and of drooling was recorded, and the heart and respiratory rates and the systolic and diastolic blood pressure were measured every five minutes for 40 minutes. All the healthy cows but only five of the 15 cows with BSE became sedated, and the period between the administration of xylazine and the onset of sedation was twice as long in the cows with BSE than in the healthy cows (15.0 [7.5] and 7.6 [2.6] minutes). Throughout the observation period, the blood pressure of the cows with BSE was significantly higher than that of the healthy cows, and the blood pressure of the healthy cows, but not of the cows with BSE, decreased significantly towards the end of the observation period.