Dicoumarol toxicity in neonatal calves associated with the feeding of sweet vernal (Anthoxanthum odoratum) hay.

Neonatal calves from a seasonal dairy herd in North Western Tasmania were presented for veterinary care due to mortalities and bleeding from multiple orifices. Necropsy examination revealed free blood throughout the parenchymatous organs, body cavities and connective tissues. There was no history of anticoagulant exposure, however, high quantities of dicoumarol were found in samples from hay fed to recently calved cows. No Australian cases of dicoumarol toxicity in neonatal calves have been previously documented, and dicoumarol toxicity in adult cattle would appear to be less common than in colder farming regions of the Northern Hemisphere.