Preface

Writing and constructing a major textbook is not to be undertaken lightly! Before a project such as this can even be proposed, there has to be a reason for it. ‘Why do we need a book on equine cancer medicine?’ ‘Will it help practitioners in particular to improve the quality of their practice and will it be of benefit to the horse itself as a species?’ Those were just a couple of the questions we asked before we set out on the project. It did not take long to realize that there is no other similar textbook on the subject. There are, of course, many excellent textbooks on general medicine and surgery relating to the horse and many of these have significant oncology content. There are those books that are focussed on one particular anatomical system or syndrome. Lameness, skin diseases and dentistry are just three of them. There are dedicated textbooks dealing with infectious disease, reproductive medicine and surgery, and surgical and medical tomes that are comprehensive sources of information. The increasing specialization of equine practice is a worldwide phenomenon that has resulted in the development of dedicated training requirements in defined aspects of practice and this is both a laudable and a positive contribution to the improving standard of medical and surgical care that we provide to our patients and their owners. However, in spite of cancer medicine being a major human and small animal specialism, cancer medicine in the horse clearly lags a long way behind. A quick search on cancer on any literature database will confirm the exponential rise in publications at all levels that deal with cancer in humans, small animals and experimental conditions. Furthermore, single-case reports on equine oncological topics abound in the modern scientific literature. There is, however, no dedicated equine oncology textbook and indeed, whilst the literature is littered with ‘case reports’ and small case series, there has been no concerted or constructive effort to expand this important area of medicine.

The demographics of the equine population are changing dramatically. In the developed world, horses are increasingly being kept into old age and so with greater numbers of older horses, we have to expect greater numbers of cases of cancer in the population. Even in the developing world, significant improvements in management and care mean that horses, mules and donkeys are living for longer, and again this will inevitably mean increasing numbers of cancer cases. There is a clear need for a focussed comprehensive text on equine cancer medicine and surgery. That is our main reason for setting out to produce this book on equine oncology.

The horse remains an important aspect of human life. In places where horses are ‘pleasure and leisure’ animals, they provide enormous enjoyment and also bring financial returns to nations and to individuals. The equine industry employs vast numbers of people and equine ‘sport’ provides physical exercise for people between 2 and 90 years of age. No other sport does that!

In the developing world, the Equidae are genuinely life-saving or, at the least, life-changing. The family donkey or pony empowers women in particular and relieves human burden. The loss of a donkey or pony, for a simple rural farmer, for example, can be catastrophic, and has implications for livelihood, lifestyle and even for life itself. We have a duty to support the concept that ‘horses’ are here to stay and that, realistically, there are no viable alternatives to the equine beast of burden in vast areas of the world. Of course, the concept of ‘carbon’-guzzling machines as an alternative may be seen as a way of reducing the welfare compromises that are commonly publicized but simply fail to answer the real-life situation. It is only through improved animal welfare that we can enhance the lives of countless millions of people worldwide.

Whilst many advances have been made in almost every area of equine veterinary practice, cancer medicine has never attracted much in the way of research interest or even clinical specialization. It is a matter of considerable regret and not a little disgrace that the veterinary profession has failed to grasp this particular nettle and that equine cancer medicine attracts so little attention.

Over the last 100 years or so, there have been some significant surveys on equine tumour prevalence, which confirm that the horse suffers a wide range of neoplastic disorders but that the numerical majority of the tumours affect the skin. These tumour types are well recognized and some sort of consensus has evolved on the best treatments and management. Less has been done to try to understand the diseases themselves, even though the opportunities to do so are clearly enormous! The tumours can usually be seen, easily examined in detail and easily biopsied, and usually can be diagnosed definitively.

Modern information systems allow owners and veterinarians alike to access vast amounts of material, though much of the internet-delivered information is of little overall value. A lot of it is blatantly misleading and often positively harmful. As owners become more aware of the availability of treatments and as their access to comments and facts improves, they become more demanding. That is no bad thing – an enquiring and challenging client serves to ensure that the best possible approach is taken and means that the veterinarian must keep up to date and be aware of the latest developments in diagnostic approaches, particularly in treatment. It drives evidence acquisition, and that in turn, drives progress.

This book is arranged in three sections. Section I sets out to provide a platform for understanding the cellular basis of cancer and its aetiopathogenesis, along with the broad principles of diagnosis, treatment and management of cancer cases.

Section II sets out the finer details of the main groups of cancer in horses and provides an in-depth description of the literature and what is generally known about the various conditions. It is an attempt to bring a degree of evidence-based information into the various tumour conditions. In-depth understanding of a particular tumour type from a pathological perspective provides interest and hopefully stimulates research and the acquisition of clinical evidence. There are, of course, varying amounts of information available relating to the various tumour types; the ‘big five’ in equine cancer are: sarcoid, melanoma, (squamous cell) carcinoma, lymphoma and mastocytoma, and inevitably they are emphasized. However, here we have tried to consider even the rarest of reported tumours on the basis that something is rare simply because it is seldom encountered; and when it is encountered, we need some information about it that might help! Rare tumours offer very different challenges to the clinician, since the evidence may be sparse, to say the least. And yet evidence is only gained through critical scientific and clinical investigations. Gradually, the bricks will be laid on the walls and evidence will build up, to the benefit of the patients themselves.

We hope the Section III will provide busy practitioners with a ready reckoner in respect of the tumours that occur in each of the 10 body systems. We have tried to make this reasonably comprehensive and we hope that it will enable a clinician to diagnose at least the majority of tumours and to have rapid access to clinically useful information when a diagnosis is provided clinically or by the pathologist.

To aid this process, disease summary boxes have been included for each of the major tumour types in this final section, condensing the main points under ‘Notes’, ‘Clinical features’, ‘Diagnostic confirmation’, ‘Management’ and ‘Prognosis’ headings. Incidence is graded by colour:

common rare very rare

Colour-coding is also used to indicate prognosis:

hopeless poor guarded good

Clinicians might benefit a great deal from the pathological input, while pathologists might similarly gain from seeing the cases that they are consulted upon. The relationship between pathologists and clinicians is a vital part of the developing sphere of equine oncological medicine. We hope this will be an expanding resource to readers over the years as more cases are added to it.

Inevitably, with a broad project such as this, there is a degree of overlap and repetition between the sections but we make no apology for this, simply because the three main sections will, we believe, be read and consulted at different times under different conditions. We have set out to make it as comprehensive as we can but we have, of course, been constrained in the amount of text and the number of images we could include. We hope that the book will provide a basis for the recognition of equine oncology as a specialism and as an important and challenging clinical topic.

Cancer medicine is a serious challenge to us all and we hope this book will help to widen clinical and research interest in aspects of cancer medicine in horses for the future good of the horse. We have set out to redress the imbalance as best we can, recognizing that there is more unknown than known in equine oncology. We extrapolate at our peril, of course, but that is an inevitable result of ‘being behind’, so we call for more effort both in the clinical circumstances and in research.

We commend this book to you – there are inevitably some aspects that we have had to reduce and even exclude but we feel sure this is a constructive contribution to...