Stability of prothrombin times in sheep dosed with natural and synthetic anticoagulants.

Sheep were dosed with natural and synthetic anticoagulants to prolong prothrombin time (PT) in the one stage PT test. The stability of subsequent values of PT of up to 40 seconds was measured at various times over a 24 hour period in plasma and whole blood stored at 0, 20 and 30 degrees C, representing ideal to unsuitable conditions of sample preparation and storage. In contrast to cautions in the literature, the various treatments had little influence on PT. These findings should encourage the use of PT in field diagnosis and research in sheep by surmounting the tenet of the difficulty in effectively preserving blood samples for PT determinations.