Evidence for the role of the sheep biting-louse Bovicola ovis in producing cockle, a sheep pelt defect.

The prevalence and severity of cockle, a sheep pelt defect characterised by raised lumps, was assessed on lambs that were either louse-infested (Bovicola ovis) or louse-free at birth. Assessments were made on pickled pelts, 10 months after the lambs had entered the trial. Lambs kept free of lice did not develop cockle, whereas the defect was common in lambs (about 90%) that were infested with lice. There was a direct correlation between louse scores and cockle, high louse scores being associated with a more severe degree of cockle. The results give support to the strong causal relationship between B. ovis and cockle, but questions such as the minimum number of lice needed to cause cockle and the time required for cockle to develop still need to be answered.