[Epidemiological aspects of Chorioptes-mange in dairy cows in Switzerland: a field study].

In the canton of Freiburg, in the midlands of western Switzerland, the influence of housing systems and season on the distribution of Chorioptes-mange was studied. 24 herds with a total of 667 dairy cows held in tethered and loose housings were considered. In the 14 farms with tethered housing 33.8 % of the dairy cows were clinically suspicious and 31.0 % parasitologically positive. In the ten studied farms with loose housing 26.5 % were clinically suspicious and 17.8 % parasitologically positive cows. Statistically the infestations of the two housing systems did not differ significantly (U-test, p > 0.05). The transmission of mange occurs mainly directly from animal to animal, and chronically infested animals are considered to be the main source of infestation. The seasonality of Chorioptes-mange which is typical of our temperate climate was confirmed by serial studies made in two endemically infested farms with tethered housing.