Principles of Equine Dentistry

When horses functioned as the primary means of draft and transportation, equine dentistry was a very important part of veterinary medicine. This is evidenced by books dedicated to the subject, for example Merillat's book, Veterinary Surgery, Volume 1: Animal Dentistry and Diseases of the Mouth published in 1906. Much early literature was based on observation, categorization, and comparison. Examples include dental aging papers that date back to Girard in 1834, Simonds in 1854, and the most famous of all, Galvayne in 1886. Comparative pathology was done brilliantly by Colyer in 1936. The process of observation, categorization, and comparison might be thought of as classification and is a method common in all branches of science, medicine, veterinary medicine, and dentistry. The next stage is in-depth analysis of physiological and pathological processes and a closer look at anatomy, including histology. The early literature on periodontal disease by Little, Colyer, and Voss falls into this category. Even Aristotle made observations of periodontal disease in equines well before his time! After the introduction of motorized vehicles, equine dentistry took a back seat to food animal disease. Veterinarians were dealing with infectious diseases that affected food animal production such as hog cholera and foot and mouth disease. Horses were affected by some of these same diseases. However, the growing world population needed to be fed, and veterinarians focused principally on that problem. At this time veterinarians such as Becker made advanced innovations in instrumentation as well as beginning the next stage of scientific advancement, that is, the application to the equine patient of concepts developed in dentistry of other species. Becker's motorized instruments are still envied by equine dental practitioners today. The many dental impressions he took were examples of application of human dental principles and materials to the equine patient. After World War II, many parts of the world, especially the US, engaged in economic progress and a financial boom occurred. The result was acquisition of disposable income and equine medicine regained its importance. Evidence of this fact is the formation of the American Association of Equine Practitioners in 1954. People had money to spend on performing horses, and equestrian vocations were either born anew, or expanded significantly. Equine veterinarians were busy keeping these performers sound and able to do their jobs. While areas of lameness, reproduction, and surgery were rapidly developing, dentistry remained less important, and advancement stagnated. As time went on, a handful of individuals recognized the need for dental care in performing horses and proceeded to fill that niche. Jeffrey, Moriarity, and others who were not veterinarians revived and advanced equine dentistry, with an eye towards bitting comfort. The stages of advancement overlapped. The second stage of in-depth investigation continued in the 1970s as Baker presented his landmark works. Continuing to current times and knowledge, Dixon and his group, including Kilic and Dacre, made significant contributions with descriptions of dental histology and comparison of normal teeth to diseased teeth. This trend continues in this group today with du Toit's current efforts. They have exponentially advanced knowledge of tooth structure and function. Continuing to advance the third step in scientific advancement, which we will call cross-species application of dental principles, Dr. Peter Emily pioneered application of human dental principles to all veterinary patients, including the horse. Easley and others have continued the process especially in the area of endodontics, where Easley and Emily collaborated on many surgical endodontic cases. This book identifies principles found in the world of general dentistry and applies them to the equine species. Since the vast majority of knowledge is based on, and especially the body of literature is comprised of principles of brachydont (human and small animal) dentistry, those principles need to be learned and evaluated in relation to the hypsodont (equine) patient. Their study leads to an understanding of equine dentistry that in many cases fits equine problems, their pathogenesis, evaluation, diagnosis, treatment, and prognosis quite well. When a system, for example, of evaluating the stages of periodontal disease has been well established in brachydont dentistry, it seems to the editor that such an application should be measured in the equine species and its fitness determined. There is no reason to ignore such a system just because it has never before been used in the equine patient. Such a system actually works very well and provides three major benefits: it provides a vocabulary with which equine dental practitioners can communicate with those in the brachydont world; it nullifies the need to 'start from scratch' in staging equine periodontal disease; and it provides a baseline for understanding the disease process itself. There are many situations where brachydont principles cross species lines. Some are not intuitively obvious, others are. Additionally, many principles that one would assume to cross from brachydont to hypsodont, in fact, do not do so. It is the purpose of this book to identify dental principles, measure them in clinical equine cases, and evaluate the results. Ideas and principles held dear today become fodder for late night chuckles tomorrow. Other concepts disregarded today become facts of tomorrow. As with all other fields, dentistry continues to evolve. It is hoped that the reader will consider with an open mind the principles of dentistry related to equine patients as discussed in these pages, and continue the process of bringing the larger world of dentistry into that of the equine patient.