Unusual findings in ovine cerebrospinal fluid

History: The ewe was a homebred breeding ewe on a farm in the Scottish Borders. The flock was composed of 530 ewes and 150 ewe hoggs which were housed from January to April. The ewes had been dosed for liver fluke in the previous autumn but not treated for worms, and had no worm treatment at lambing. Nematode parasites were effectively controlled by integrated evasive/anthelmintic strategies and fluke was controlled with 2 or 3 treatments per year. The farmer noticed the ewe was recumbent in the field. This was the only animal affected at that time but several ewes had died over the grazing season, on the same field, and these occurrences had not been investigated. This field is situated by a river in the middle of a large village, and is used by many members of the public for walking their dogs. The ewe was first examined on farm on the 7 th October 2009.