NR ANCF
AU Munro,R.
TI Neural tissue embolism in cattle
QU The Veterinary Record 1997 May 17; 140(20): 536
PT letter
VT
Neural tissue embolism in cattle
SIR, - Neural tissue embolism in the lungs of two cattle was an unexpected finding, by a USA Food Safety and Inspection Service (FStS) pathologist, in a retrospective study of lung pathology. Subsequently, Garland and others (1996) in the USA reported neural embolism in 2.5 to 5 per cent of an unstated number of cattle stunned by a pneumatic actuated penetrative captive bolt gun. In human beings, embolism of central nervous system (CNS) material to the lungs is an unusual or rare event. Individual cases have been recorded following severe head injury but there have been few surveys to calculate the prevalence of this condition. Oppenheimer (1954) found no examples in 277 cases but McMillan (1956), in a series of full necropsies of 213 consecutive cases of fatal head trauma, encountered four instances of nervous tissue embolism.
In order to shed further light on the embolism of CNS material to the lungs of cattle which had been stunned by captive bolt humane killers, two studies involving a total of 210 adult cattle were conducted in Great Britain in 1996. A pilot study examined, in detail, the lungs from 10 cattle from one abattoir in Scotland. Whole lungs were collected immediately after slaughter and each bronchopulmonary segment of the lung was subject to multiple sectioning, and the branches of the pulmonary blood vessels were followed and opened as far as practicable. Blocks of tissue from each of 18 main bronchopulmonary segments from each animal were examined histologically. No emboli were found during the course of the gross and microscopic examinations.
In view of the observations made during the pilot study and of the findings of the pathologists who reported neural emboli in bovine and human lungs, it was considered that gross examination of the whole lung plus histopathology on four selected blocks of lung, two from apical and two from diaphragmatic lobes, would be a practical and satisfactory method of screening lung for emboli. The specific areas of lung to be examined histologically were selected for four main reasons.
(1) In the human cases and in the cattle examined by the FSIS pathologist, neural embolism was more commonly found in the diaphragmatic lobes than elsewhere.
(2) The apical lobes of the bovine lung are served by major branches of the pulmonary artery and it would be unreasonable to assume that some emboli arriving from the right ventricle of the heart would not pass into the anterior lobes.
(3) It had been determined, in the pilot study, that the chosen sites consistently contained a range of pulmonary arteries and arterioles and that these would be sectioned in an appropriate plane for examination.
(4) The sites chosen had to be readily identifiable by the veterinary investigation officers who would be sampling the lungs to ensure consistency among the submissions from different laboratories.
Twenty lungs were collected and sampled from each of 10 abattoirs in England and Wales. One hundred and ninety-nine of these animals were shot with cartridge-activated penetrating captive bolt guns. A free bullet was used on one bull. Compressed air weapons were not used in any of the abattoirs involved in the survey. One hundred and forty (70 per cent) of the animals were pithed. The remaining 60 animals were from three abattoirs where pithing was not routinely practised. No evidence of embolism was found in any of the samples.
Although the number of animals (210) examined in this investigation was limited, it is pertinent that it is similar to the number of cases in the human head trauma survey. The results of the study suggest that if embolism of neural tissue to the lungs of cattle occurs under the conditions prevailing in Great Britain, it is an uncommon event.
The help of the State Veterinary Service and the Veterinary Investigation Division of the Veterinary Laboratories Agency in collecting the samples and information on slaughtering is gratefully acknowledged.
Ranald Munro, Lasswade Veterinary Laboratory, Bush Estate, Penicuick, Midlothian EH26 OSA
References
GARLAND, T. D., BAUER, N. & BAILEY, M. (1996) The Lancet 348, 610
McMILLAN. J. B. (1956) American Journal of Pathology 32, 405
OPPENHEIMER, E. H. (1954) Bulletin of Johns Hopkins Hospital 94, 86
IN Der Autor berichtet von einem US-Pathologen (McMillan,J.B.; American Journal of Pathology 1956; 32: 405), der schon vor Garland et al. Nervengewebe in den Lungen zweier Rinder fand. Tam Garland wußte nach eigener Aussage zumindest bis zum 16.2.2000 nichts davon. Der Autor zitiert auch eine 1954 von Oppenheimer (Oppenheimer,E.H.; Bulletin of Johns Hopkins Hospital 1954; 94: 86) publizierte Untersuchung von 277 nach schweren Hirntraumen gestorbenen Patienten, bei denen kein Nervengewebe in der Lunge gefunden wurde. Eine 1956 von McMillan publizierte Untersuchung von 213 nach schweren Hirntraumen gestorbenen Patienten lieferte hingegen 4 Fälle mit Nervengewebe in der Lunge. Nun berichtet der Autor über eine 1996 in Großbritannien durchgeführte Untersuchung von 210 mit einem Bolzenschußapparat auf das Ausbluten vorbereiteten Rindern. Bei 10 Tieren aus einem schottischen Schlachthof folgte man so weit wie möglich jedem Bronchialzweig und fand nichts. Daraufhin wurden die Lungen der restlichen 200 Rinder aus 10 Schlachthöfen in England und Wales nur oberflächlich untersucht und lediglich jeweils 4 ausgewählte Blöcke wurden einer histologischen Kontrolle unterzogen. Man fand bei dieser ziemlich oberflächlichen Suche kein Hirngewebe. Mit einer Ausnahme waren die Rinder alle mit Bolzenschußapparaten betäubt worden, deren Sprengladungen den Bolzen durch die Schädeldecke treiben. Bei 140 der 200 Tiere (70%) wurde zusätzlich mit einer durch das Schußloch eingeführten flexiblen Stange das Stammhirn zerstört.
MH Animal; Cattle; Cattle Diseases/*etiology; Firearms; Intracranial Embolism and Thrombosis/etiology/*veterinary; Lung/pathology; *Nerve Tissue; Pulmonary Embolism/etiology/*veterinary
SP englisch
PO England
OR Prion-Krankheiten M
ZF kritische Zusammenfassung von Roland Heynkes