[Endoparasites--prevention in ungulates in fenced enclosures: experiences with a pilot project in the Dählhölzli Zoo in Bern].

In the animal zoo Dählhölzli Berne all ungulates are continuously monitored since 1984 (qualitatively and quantitatively) in the context of an epidemiological study on gastrointestinal strongyles. Fecal sampling occurs every two weeks in the "parasite risk group", every four to six weeks in the so called "non-risk group". Risk group-animals repeatedly show increased fecal egg counts, whereas among non-risk group-animals only ascarid eggs in Przewalski-horses and wild boars can become significant. The animals are treated (metaphylactically) only at a high egg production or at a steadily increasing egg production. A resulting slight but constant reinfection allows the build-up of an immunity, leading thereby to a decreased frequency of treatment. During the monitoring period (1984-1990) only four animals out of 80 post-mortem analysed animals had a diagnoses of an endoparasitoses as a cause of death.