Plants Poisonous to Horses An Australian Field Guide HOR - 06-048 Plants Poisonous to1 1 2/06/2006 9:25:44 AM xxxxx HOR - 06-048 Plants Poisonous to2 2 2/06/2006 9:25:44 AM Plants Poisonous to Horses An Australian Field Guide Mellisa Offord RIRDC Publication No 06/048 RIRDC Project No. OFF-1A HOR - 06-048 Plants Poisonous to1 1 2/06/2006 9:25:45 AM Disclaimer by RIRDC Disclaimer by author The information contained in this publication is intended for The information presented in this publication are intended as a general use to assist public knowledge and discussion and to guide to the plants in Australia that are poisonous to horses. All help improve the development of sustainable industries. The care and diligence has been exercised in interpreting published information should not be relied upon for the purpose of a information as the basis for the information presented in this particular matter. Specialist and/or appropriate legal advice book. should be obtained before any action or decision is taken on Specific circumstances and research findings after the date of the basis of any material in this document. The Commonwealth publication may influence the accuracy of the infomation within of Australia, Rural Industries Research and Development this book. The author accepts no responsibility and disclaims Corporation, the authors or contributors do not assume liability any liability for any error, loss or unforeseen consequence that of any kind whatsoever resulting from any person’s use or may arise from relying on, or adopting, any of the information in reliance upon the content of this document. this publication. This publication is copyright. However, RIRDC encourages wide dissemination of its research, providing the Corporation is clearly acknowledged. For any other enquiries concerning reproduction, contact the Publications Manager on phone 02 6272 3186. In submitting this report the researcher has agreed to publishing this material in its edited form. RIRDC contact details Researcher’s contact details Level 2 Mellisa Offord 15 National Circuit PO Box 461 BARTON ACT 2600 Forestville NSW 2087 PO Box 4776 Phone/Fax: 02 8901 0622 KINGSTON ACT 2604 Phone: 02 6272 4819 Fax: 02 6272 5877 Email: [email protected] Web: www.rirdc.gov.au Published in June 2006. Publication design and graphics by Mellisa Offord. Cover design by RIRDC Publications. Edited by Karen Drake. Sydney 02 9453 2420 ©2006 Rural Industries Research and Development Corporation All rights reserved ISBN 1440-6845 ISSN 1 74151 311 1 Plants Poisonous to Horses - An Australian Field Guide Publication no. 06/048 Project no. OFF-1A Front and back cover photograph: Mellisa Offord II HOR - 06-048 Plants Poisonous to2 2 2/06/2006 9:25:45 AM Foreword Many plants that grow in Australia are potentially poisonous to horses. Such plants can cause considerable economic and welfare problems for horse owners. Under most circumstances, horses will avoid consuming toxic amounts of poisonous plants. However, some poisonous plants are palatable to horses and some need only be consumed in very small amounts to cause poisoning. Horses may choose to eat poisonous plants when there is little alternative forage. Also, seasonal conditions may influence the toxicity levels of certain plants, making them more deadly at various times of the year. An awareness of toxic plants growing in Australian and an understanding of the factors that influence the risk of poisoning will help horse owners keep their horses safe. Pasture management decisions and landscaping decisions should be made with consideration to plants that are potentially poisonous to horses. This book is designed as a guide for horse owners to help them prevent plant poisoning in their horses. It clearly outlines the factors that influence the risk of plant poisoning and the ways to reduce this risk. The types of toxins that can be found in plants are discussed, along with the signs of poisoning that may be seen in horses that have ingested toxic plant material. A description of each plant is provided, including structure, growth habit and identifying features. Management notes suggest ways of dealing with poisonous plants on properties. The book includes a comprehensive list of ornamental plants that are known to be toxic to horses. The reference list is a useful resource for further reading and includes the journal articles, industry papers, books, CD Roms and Internet resources that were used to create this publication. The production of this book was funded through industry revenue which was matched by funds provided by the Australian Government. This book, an addition to RIRDC’s diverse range of over 1500 publications, forms part of our Horse R&D program, which aims to assist in developing the Australian horse industry. Most of our publications are available for viewing, downloading or purchasing online through our website: • downloads at www.rirdc.gov.au/fullreports/index.html • purchases at www.rirdc.gov.au/eshop Peter O’Brien Managing Director Rural Industries Research and Development Corporation III HOR - 06-048 Plants Poisonous to3 3 2/06/2006 9:25:45 AM Acknowledgments I would like to acknowledge the following people and organisations for their support in the production of this book. The Rural Industries Research and Development Corporation. Jane Vincent and John Freestone for their continued support and encouragement in the production of this publication. Ross McKenzie for supplying photos and for reviewing the publication and offering expert toxicology advice on many of the plants in the book. My family for their support and encouragement. In particular I would like to thank my sister Cathy Offord and my mother Pat Offord for their expert botanic advice. Susanne Hourigan for supplying photos and information on crotalarias. Matthew Smyth for supplying photos and information on Paterson’s Curse. Many thanks go to the individuals who contributed photos. In particular I’d like to thank Ken Harris and Sheldon Navie for allowing me access to their extensive photo collections. I would also like to thank Paul McGreevy, Peter Windsor, Mary Alice Mitchell and Calder Chaffey for their contributions. Those that have no acknowledgement have either been supplied by myself or RIRDC. Reuben Rose for his encouragement and feedback on the content of the book. Barbara Wiecek for advice and information on plant identification. IV HOR - 06-048 Plants Poisonous to4 4 2/06/2006 9:25:45 AM Table of contents The risk to horses from poisonous plants ...............................1 Controlling poisonous plants.................................................................2 Naming plants ........................................................................................................ 4 Identifying plants ................................................................................................5 Using this book .....................................................................................................6 Alkaloids Pyrrolizidine alkaloids................................................................................................7 Paterson’s curse ....................................................................................................................... 8 Crotalarias ................................................................................................................................ 9 Senecios ................................................................................................................................. 12 Heliotropes ............................................................................................................................. 14 Amsinckias ............................................................................................................................. 16 Tryptamine alkaloids ................................................................................................17 Blue canary grass ................................................................................................................... 17 Paradoxa grass ...................................................................................................................... 17 Indolizidine alkaloids ...............................................................................................18 Swainsonas ............................................................................................................................. 18 Taxine alkaloids ..........................................................................................................20 English yew ............................................................................................................................. 20 Tropane alkaloids.......................................................................................................21 Field bindweed ...................................................................................................................... 21 Thornapples ........................................................................................................................... 22 Angel’s trumpet ...................................................................................................................... 23 Poison corkwood ................................................................................................................... 23 Corkwood .............................................................................................................................