Understanding the Horse's Teeth and Mouth E-Book

Andy Peffers

• Herausgeber: Crowood
• Kategorie: Lebensstil
• Sprache: Englisch

Veröffentlichungsjahr: 2016

Beschreibung

Over thousands of years the horse's teeth have evolved to be hard-wearing and efficient in biting through plant material and grinding food to make it digestible. However, man's domestication of the horse has resulted in numerous potential problems in this area, with ill-fitting bits and inappropriate diet, as well as natural factors such as disease, parasites and old age all posing potential hazards. Understanding the Horse's Teeth and Mouth explains in accessible terms what equine dental care involves, why good dental care is important for the horse and how oral conditions can affect not only the way the horse eats, but also its health, behaviour and movement. Topics covered include: Dental anatomy; Bits and bitting; Rasping; Pathologies and how to treat them; Nerve blocks and techniques for tooth extraction; Procedures such as filling horses' teeth. Superbly illustrated with 150 colour photographs and 20 diagrams.

Leseprobe

Understandingthe Horse’sTeeth and Mouth

Andy Peffers

THE CROWOOD PRESS

First published in 2016 by

J.A. Allen

Ramsbury, Marlborough

Wiltshire SN8 2HR

J.A. Allen is an imprint of The Crowood Press

www.crowood.com

This e-book first published in 2016

© Andrew Peffers 2016

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publishers.

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

ISBN 978 1 90880 953 7

Acknowledgements

Many people have helped and contributed to the production of this book. I am indebted to them all. First my Mum and Dad, for always being there with support and encouragement. My wife Mandy, who has patiently read everything I have written and has been very generous with her help and advice. My children Hamish and Archie, who have helped out with technological issues and have endured me taking more photos of horses’ teeth than of them. My equine veterinary nurse assistant Emily, who has had to tolerate years of misery working alongside me – it is her fingers and hands that you see often in this book holding horses’ tongues and cheeks while I take photographs. Emma Humphries, who has produced all the wonderful illustrations for this book. All the academics, professors and fellow vets who have helped with advice and allowed me to use their cases and photographs, especially Prof. Paddy Dixon, Prof. Derek Knottenbelt, Prof. Debbie Archer, Pete Ravenhill, Jeremy Kemp-Symonds and Fiona Jones from RD Owen Equine. The British Association of Equine Dental Technicians and all its members have given me lots of support over the years, but particularly Victoria Hammond for the use of her case and the local EDTs with whom I work closely: Robin Harding, Ivan Stockdale, Rebecca Hughes, Jess Collard and Geraint Hughes. Lastly this book would not have been possible without the hard work of the team at Crowood Press.

Contents

1     THE DEVELOPMENT OF EQUINE DENTISTRY

2     BITS AND BItTING

3     THE HEAD

4     DENTAL ANATOMY

5     RASPING A HORSE’S TEETH

6     DENTAL EXAMINATION

7     RASPING EQUIPMENT

8     PERFORMING DENTAL RASPING

9     DENTAL PATHOLOGY

10     DISEASES AFFECTING THE HEAD AND NECK

11     SEDATION, NERVE BLOCKS AND EXTRACTIONS

12     DIAGNOSTIC IMAGING

Glossary

Bibliography

Index

1  The Development of Equine Dentistry

TRACING THE EVOLUTION OF THE HORSE BY THEIR TEETH

Hyracotherium

The horse (family Equidae) first appeared 56 million years ago in the Eocene era. The first Equidae were Hyracotherium. These were forest dwellers; they were about the size of a small dog and weighed about 5kg. They were browsers feeding mainly on the soft leaves of bushes, berries and other vegetation. Their teeth were short crowned (brachydont) like human teeth because they were not subjected to intense wear. They had four premolars and three molars. The premolars were small and triangular, whereas the molars were squarer with a greater surface area for grinding.

Illustration of Hyracotherium.

Mesohippus

Mesohippus lived 40–30 million years ago, weighed less than 100kg and were also forest dwellers. The crown length of the teeth was still short but the premolars had become ‘molarized’ – they were larger and squarer with enamel infoldings to increase the grinding surface area. Their teeth shape and microwear indicates a specialized diet of leaves now from a temperate rather than tropical forest.

Merychippus lived 20–10 million years ago, and were very much bigger, weighing over 100kg. The diet was now predominantly grass, grazing on the tough fibrous grasslands that were expanding, replacing the forests, although carbon analysis of teeth from this time demonstrated that they were mixed feeders and would still browse if food was scarce. To adapt to the tough fibrous diet Merychippus had high crowned (hypsodont) teeth and their skull and jaw was deeper to accommodate these longer teeth. The cheek teeth also had a larger surface area than Mesohippus.

Equus

Modern Equus first appeared about five million years ago, were larger again than Merychippus and mainly fed by grazing the tough grasslands. Their teeth were long and hypsodont and the surface area of the cheek teeth was increased even more than merrychippus. Equus also had an elongated and deepened skull and jaws adapted for grazing.

Therefore over 50 million years the horse evolved spreading across four continents and showing a greater than 60-fold increase in maximum body mass. In order to meet the increased energy demand needed by the large body mass, and also to counteract the increased dental attrition caused by eating a fibrous diet, the horse’s teeth evolved – from brachydont short crowned teeth to hypsodont long crowned teeth. The premolars became more square and molarized, and all the cheek teeth increased in width and depth to increase the grinding surface area. As the horse evolved and its body size increased its life span increased as well, from less than five years to over twenty; therefore the teeth had to remain in use for longer.