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Contents

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This atlas is dedicated to Odette Rebecca Coulson, Arlene’s young daughter who died in April 2001. Her good humour, artistic suggestions and flexibility in demands on her mother’s time were as invaluable as the encouragement of her husband Andrew.

Preface

In compiling the second edition of this atlas the authors have concentrated on improving the reproduction of many of the radiographs included in the first edition. Some radiographs have been replaced and additional variant, ‘pitfall’, and contrast study radiographs are included.

New line and schematic drawings accompany a number of the radiographs and will be seen to follow the original format. The reader will also find a series of drawings constructed, for the second edition, which act as guidance for normal radiographic shadow sizes.

The text formatting has been reviewed to improve referencing of key points in the more lengthy legends. Additional labelling of some radiographs has been made for text clarity.

A comprehensive contents list has been included prior to each section and page headers expanded to detail the radiograph illustrated.

Introduction

Aim of the book

The primary aim of this book is to provide a detailed reference for the basic radiographic anatomy of the dog and cat. This is achieved by the inclusion of both radiographs and drawings.

The immature animal and, where relevant, a spectrum of breeds have been included.

A selection of anatomical variants and a few of the more common radiographic ‘pitfalls’ are also to be found following the ‘normal’ radiograph.

Following the anatomical sections of plain radiography is a series of the more commonly employed contrast studies. Confusion can occur when trying to interpret such techniques, and many anatomical features can only be seen with the aid of contrast agents. Hence these have been included, hoping they aid evaluation of the studies performed more regularly in general practice. In addition a few of the less common studies are found for anatomical understanding.

From personal experience in teaching and examining veterinary surgeons for postgraduate radiology certification it is clear that a good basic knowledge of radiographic anatomy is essential. Unfortunately, all too often ‘normality’ is not recognised, especially where breed variation has to be considered.

A short bibliography is in the last few pages of this book. The list includes only books and publications consulted, and relevant, for the figures and text of this manuscript. No individual references are cited in the text.

No index has been included as the atlas is intended to be used as a visual reference for normality. To facilitate this a comprehensive contents list, divided into anatomical regions for plain and contrast radiography, is provided.

Although initially it would appear that the book is mainly for the benefit of veterinary surgeons wanting to obtain additional radiology qualifications, basic radiographic anatomy will be of value to both undergraduates and veterinary surgeons in general practice. It is hoped that this atlas will become a useful and well used reference book for both the specialising and nonspecialising veterinary audience.

Drawings

The line drawings follow tracings of the radiographs. Only shadows seen in the radiograph have been traced, even if anatomically more detail should have been present. Each drawing has a detailed key.

It is hoped that the radiographic reproduction is of a sufficient standard to allow recognition of all the radiographic shadows that have been traced.

Where the shadows are complex, as in the skull, a number of drawings have been made to avoid interpretative confusion of numerous lines within small regions.

Every effort has been made not to overdraw or over-label the drawings correlating to the radiographs. In this way it is hoped that the reader will quickly recognise the important shadows and become familiar with radiographic anatomy.

Separate line drawings have also been included of soft tissue structures surrounding bony shadows. These structures are often overlooked when attention is focused on the more obvious opaque shadows. Much valuable information can be gained from the soft tissue surrounding, for example, the stifle joint.

In addition to the line drawings, schematic drawings of many projections have been made to familiarise the reader with anatomical features not visible on the radiograph. In this way the reader will be more able to make logical diagnosis/differential diagnosis when faced with radiographs demonstrating abnormal features.

Animals

Most of the radiographs in this book are original and for the exclusive use of the authors. The remainder have been given to the authors by generous colleagues.

The radiographs have been obtained over a period of five to six years and a brief summary of their source follows.

The ‘normal’ dog radiographs are mainly from a group of Beagle Hounds while the ‘normal’ cat radiographs are from a number of individual British Domestic Short Haired cats.

In both cases the radiographs were obtained specifically for the book, radiography taking place in conjunction with routine surgery or dentistry requiring general anaesthesia.

The different breeds, anatomical variants and radiographic ‘pitfall’ radiographs were either obtained primarily for this book or were taken from veterinary college files. This was probably one of the most difficult sections to complete for publication as radiographs falling into ‘variant’ or ‘pitfall’ are not usually recorded.

The dog juvenile section was commissioned for this book and radiography was performed on the same dog (Samoyed crossbred entire male) from 1 month to 15 months of age at intervals of 1 month.

This is probably the ideal situation for a juvenile study as individual, feeding and housing variations are all under control.

The study was based at University of Guelph in Ontario Canada under the watchful eye of Professor Sumner-Smith.

The cat juvenile section usually involved a different cat at each monthly age. Individuals from a breeding group were radiographed specifically for this book, during studies on clinical anaesthesia based in Newcastle, England.

Although this is not ideal as some individual variation is present, variations with feeding and housing were eliminated. The significant advantage of undertaking the work in this manner has been to ensure consistent anaesthetic and radiographic techniques in producing the final radiographs. Radiography was from 4 weeks to 96 weeks of age at four-weekly intervals.

All cats were entire and it was interesting to see the differences in bone size between male and female cats. The latter is especially relevant with the skull section.

The contrast study section radiographs were obtained from college files spanning over 20 years from 1975 to 1995. It was not thought to be ethical to introduce contrast medium, of any type, into a normal animal for the sole purpose of this book.

Radiography

All radiography performed in England, specifically for this book, was under the Ionising Radiation Regulations of 1985.

Every effort has been made to include only radiographs of a high radiographic quality.

As a variety of X-ray machines and accessory equipment have been used, no specific details of the equipment, nor exposure details, are included in this book.

A comprehensive description of radiographic positioning of the animal has purposely been excluded as there are a number of excellent books on this subject. In addition it is not the main objective of this atlas to teach positioning.

Instead a line drawing, from a photograph of the live ‘normal’ dog being radiographed, is to be found below the relevant radiograph. Positioning for the ‘normal’ cat will be similar.

The centre point for the primary beam has been indicated on each drawing by a symbol varying with the photographic exposure angle.

Normality

The quest for radiographs showing classic and completely ‘normal’ radiographic anatomy proved to be very difficult in a number of skeletal regions. So much so that it was decided to include some radiographs which demonstrated normal radiographic shadows of the bones which were to be detailed in the keys but had evidence of degenerative signs elsewhere.

In every case the bony degenerative changes were causing no clinical signs. The reader is reminded that during radiological analysis of clinical cases, over-interpretation of obvious chronic bony degeneration can result in failure to observe active bony changes elsewhere. In their early stages acute skeletal lesions are soft tissue alterations followed by subtle bony changes.

In the case of the stifle joint of the cat the absence of a bony shadow for the medial fabella of the m. gastrocnemius was commonplace. A craniocaudal shadow of the femur has been included for the sole purpose of showing this medial sesamoid bone.

With regards to the soft tissue radiographs of particular note is the cat thorax which showed considerable cardiac shadow variation.

In addition to the cardiac shadow abnormal lung opacities were commonly seen, especially affecting the right middle lung lobe.

Radiographs of these lung opacities have not been included in the book as it was considered to be too close to disease patterns, but unexpected radiographic findings in seemingly clinically normal animals are something of which the reader should be aware.

Care has been taken to indicate variation of ‘normal’ radiographic anatomy, plus bony degenerative changes. Also a full range of what would be expected as ‘normal’ is included in the book.

Acknowledgements

This book could not have been possible without the support of a vast number of people.

An enormous thank you to Dr Ray Ashdown, East Sussex, UK, our anatomical and terminological consultant, for his vast knowledge which has made such a vital and valuable contribution to this book and which has been offered so patiently during the preparation of this material.

Mr Jonathan Clayton-Jones, London, UK, has prepared the numerous drawings, line and schematic, based on the original tracings prepared by the authors. These represent the culmination of many drafts and re-drafts to reproduce satisfactorily for publication. Without his skill and patience the interpretation of many of the radiographs to the satisfaction of the authors would not have been possible.

Janet Butler at the Animal Health Trust, Newmarket, UK has provided her expertise in preparing photographs from many of the original radiographs.

Mr David Gunn at the Royal Veterinary College, London, UK has kindly allowed line drawings to be prepared from photographs of radiographic positioning prepared at the College.

Our special thanks are extended to a number of veterinary surgeons in general practice and academia who at the time persevered with obtaining normal radiographs to fill the gaps for the book.

Academic colleagues from:

Practitioner colleagues from:

Companies for providing copious quantities of radiographic film: 3M, UK and Fuji UK.

Acknowledgements

The authors would like to thank Mr Jonathan Clayton-Jones for his continued excellent interpretation of the draft drawings.

Replacement and new radiographs have once again been generously supplied by:

Dr Christine Gibbs, University of Bristol School of Veterinary Science, Bristol, UK

Jo Arthur, Downlands Veterinary Group, Bognor Regis, West Sussex, UK.

Additional practitioner colleagues from:

PDSA, Pet Aid Hospital, Leicester, Leicestershire, UK in particular Richard Ewers

NH & FM Harcourt-Brown Ltd, Harrogate, North Yorkshire, UK in particular Nigel and Tom Harcourt-Brown

Howe, Starnes, Gatward & Blowey, Uckfield, East Sussex, UK in particular Andrew Wood