Equine dental disease – no longer a neglected field of study

In the late 1800s and the early 1900s, a time when the importance of working horses was at its peak, most veterinary work was equine-related and the curriculum in veterinary colleges was largely oriented towards the horse. A great interest in equine dentistry also developed during this period. At least four equine dentistry books in the English language were published during this time (Easley 2020), including Merrillat’s seminal equine dentistry text published in the USA in 1916 (Merrilat 1916). Merrilat was rightly sceptical about some of the quack dental ‘treatments’ performed at that time such as ‘incisor reductions’ that were allegedly performed ‘to prevent the incisors from keeping the cheek teeth out of contact’ but stated ‘It was easier to trim the incisors and collect fees than to give a lecture on anatomy without pay’ (Merillat and Cambell 1935). Sir James Colyer, a human dentist and historian, who was Dean of The Royal Dental Hospital in London performed some important dental surveys on working horses in the early 1900s. He had plenty of subjects to choose from, with 100,000 carriage and dray horses working in London at that time, and he showed a high prevalence of periodontal disease in these working horses (Miles and Grigson 1960). During this same period, many innovative equine dental instruments were designed by veterinary surgeons including by Hauptner and Gunther in Germany and by Hausmann and McPherson in North America. Some of these outstanding instrument designs are still in use today (Easley 1999, 2020). However, the advent of the internal combustion engine caused a major and continuous decline in horse numbers throughout the 1900s and this also caused a decline in most scientific equine studies, including in equine dentistry (Dixon 2017). One exception was the research and clinical work of Erwin Becker, an innovative German veterinarian who performed disease prevalence surveys and gross pathological studies on equine dental disorders (Becker 1962). Otherwise, most of the mid-1900s was a barren time for all types of equine studies. During this period, the university curricula reflected this trend with the emphasis now turning to farm animals and later to small animals. During this time, veterinary students were taught little or nothing about dentistry in the veterinary schools, for example, a single lecture on cheek teeth repulsion, was the total dental course in the author’s veterinary school in the early 1970s. In general veterinary practice, dentistry was largely ignored except for a few veterinarians who repulsed apically infected and fractured teeth and cut and floated major dental overgrowths, i.e., all major disorders that were of such serious clinical concern that they could not be ignored. The improving global economic climate in the second half of the 20th century and increased leisure time for many people led to a resurgence of interest in horses, no longer for transport and agricultural uses but now for recreation and sport. These increasing horse numbers led to a revival of equine veterinary attention. A new scientifically driven interest in the 1960s led in the founding of the American Association of Equine Practitioners (AAEP) and the British Equine Veterinary Association (BEVA). Subsequently, there were major scientific and clinical developments in many equine specialities, especially in the orthopaedic, respiratory and reproduction fields. In contrast, with the exception of a handful of authors including Hofmeyr (1960), Honma (1962) and Baker (1970), minimal scientific advances were made in equine dentistry between the 1940s 1980s. In 1993, Peter Rossdale, the editor of the Equine Veterinary Journal (EVJ), with his usual far-sightedness, recognised the deficit of scientific articles on equine dentistry and devoted an issue of EVJ’s sister journal, Equine Veterinary Education (EVE) to equine dentistry that contained an editorial ‘Equine dental disease – a neglected field of study’ (Dixon 1993). This edition of EVE contained some original scientific papers on equine dentistry (that were collected with great difficulty! ) and included an article by John Walmsley in the UK, who was the first author to critically show the inaccuracy of ageing of horses by incisor examination (Walmsley 1993). More importantly, this EVE edition encouraged other veterinarians to research and report on equine dentistry. Thankfully, there has been a major revival in scientific equine dental studies since that date including as follows: gross pathological studies by Wafa in Ireland (Wafa 1988). Seminal work by Drs Kilic, Dacre and du Toit (Kilic et al. 1997; Dacre et al. 2008; du Toit et al. 2008), and clinicians in Edinburgh (Dixon et al. 2000a,2000b); Vlaminck (2008) in Belgium; Stasyzk et al. (2006) and Bienert (Kern et al. 2017) in Germany; Simhofer et al. (2008) in Austria and from American authors including Easley (1999); Easley et al. (2016). Hundreds of equine dental papers and textbooks devoted to equine dentistry have been published since the publication of that dental edition of EVE in 1993. The collection of 25 equine dental articles previously published by EVE in the current Equine Dental Disease online collection is testament to that revival in equine dentistry that thankfully, shows no signs of abating.