Investigation of the vaginal smear (Allen-Doisy) assay of oestrogen in ovariectomized ewes

Abstract

The vaginal smear (Allen-Doisy) assay for oestrogens has been studied with ovariectomized ewes. Variation between ewes was considerable and the slopes of the log dose-response lines were low. The value of the assay for quantitative determination of oestrogen is limited by lack of precision. The oestrogenic content of red clover (Trifolium pratense) was estimated in terms of micrograms of injected stilboestrol per kilogram of dry matter.

Considerable variation in sensitivity to the standard was observed. Intraruminal administration of stilboestrol reduced its activity about 100-fold compared with subcutaneous administration. Ewes were given carbon tetrachloride to cause liver damage but the vaginal response to red clover was not altered.