Houndstongue (Cynoglossum officinale) in pasture - a health hazard for horses.

Meteorism and colics were observed in horses after grazing on young pasture . The botanical analysis of a sample as taken by the owner revealed a great diversity of grasses, herbs and legumes. Houndstongue (Cynoglossum officin ale) in its rosette stage was identified in amounts of 1 % of the total sam ple, although this cannot be regarded as representative for the composition of the green fodder. This plant has been reported to be highly toxic for h orses and other species, mainly during the early growth stadium due to its contents of pyrrolizidin alkaloids with a strong hepatotoxic activity. In t he present case it remained unclear, whether the horses actually ingested t his poisonous plant in relevant amounts. In general it has to be emphasised , that a contamination especially of hay or silage bears a severe risk for horses. The contamination of green fodder with houndstongue can be a seriou s problem for the feeding practice in certain regions (dry grassland, loess or shell lime soil, extensive management).