It has been estimated that in the UK, up to 95% of horses over the age of 15 will have some signs of dental disease. In donkeys, the prevalence of dental disease is approximately 73%, with this figure rising to 98% in older animals. Most horse owners recognise clinical signs of advanced dental disease such as nasal discharge, facial swelling, quidding or anorexia. However, it is important to realise that many horses will suffer in silence and display very few or very subtle symptoms. One survey demonstrated that as few as 31% of owners correctly suspected dental disease in their horse. It is not uncommon for horses with advanced pathology to appear unaffected clinically.
Why are these figures so high?
One reason for such high rates of dental disease is that horses are simply living longer, and their teeth will begin to wear out naturally as they age. However, the most likely reason is that, as dental care advances, we as professionals have become much better at recognising subtle, early signs of disease and seeing these signs as potential problems. As horses age, the prevalence of dental disease increases, particularly from about 15 years of age, but all horses will benefit from regular care from a very early age.
What types of problems do horses get?
The most common dental issues in younger animals tend to be problems associated with normal growth, such as sharp enamel points or overgrowths. Sharp enamel points can lead to ulceration and discomfort which may manifest as behavioural issues when ridden.
Horses’ teeth erupt continuously over the lifespan of the tooth, at a rate of approximately 3-4mm per year. In the healthy mouth, these teeth are worn down at a similar rate. The most common conditions noted are abnormalities of wear, diastemata (pathological spaces between the teeth), periodontal disease, endodontic disease (caries) or a degenerative condition affecting the incisors, called EOTRH (Equine Odontoclastic Tooth Resorption and Hypercementosis). Many of these conditions will start out as subtle lesions, for example infundibular caries will only be spotted with the use of a mouth gag, headtorch and may necessitate the use of a mirror or endoscope. Recognition is much easier when the horse is sedated and standing still.
The ability to chew declines over time. The enamel surface of the teeth becomes thinner, and the teeth become smoother. This reduces the efficiency of chewing and makes teeth less resistant to wear. While there is little we can do to slow this process, regular dental care will ensure that early lesions are spotted and treated so that we can reduce the risk of other problems affecting the teeth. An aging horse will have teeth that are less efficient, but we must preserve the teeth as much as possible to ensure they maintain the ability to grind forage for as long as possible.
In addition to preservation of dental structure, regular dental examination will help to reduce the risk of painful conditions affecting the horse. As noted above, a high proportion of horses will have some form of dental disease, with many not showing clinical signs. A detailed dental examination will ensure that your horse is not suffering from pain without your knowledge.
The dental examination:
While many animals will tolerate a mouth gag and brief dental examination, it must be remembered that many of these have significant dental pathologies and may find the act of examination uncomfortable or even painful. If the practitioner examining your horse cannot get a good look, it is highly likely that subtle problems are missed. It is necessary to get a good view of the erupted surfaces of the teeth as well as the soft tissue structures of the mouth. For example, the horse may have food packed between the teeth, which must be removed to assess any damage to the surrounding periodontal tissue. This process can be extremely painful in cases with advanced disease, so it is important that sedation and pain relief or local nerve blocks are used to facilitate examination.
Advances in sedative drugs and techniques mean that it is relatively safe to induce standing sedation in most horses, even those of advanced age or suffering from other health issues or heart problems. In fact, it is often preferable to sedate a horse for the procedure to keep stress to a minimum and to reduce the time taken to carry out the examination and treatment. Sedation tends to make the procedure a more positive experience, which may in turn reduce the stress of future dental examinations. Sedation also improves safety for the owner or handler, the practitioner carrying out the procedure and the animal itself. A sedated horse can still react unpredictably but is much less likely to do so.
The vast majority of dental conditions can be diagnosed by a detailed clinical examination alone, but it should also be mentioned that some cases will need further imaging to reach a diagnosis, such as oral endoscopy, radiography or even computed tomography.
In summary, regular, routine dental examination is a vital part of equine care. Careful, methodical examination with good visual access will ensure early recognition of dental problems, many of which can be treated effectively to reduce the risk of advanced dental disease or pain.
References and further reading:
Nicholls, V.M. and Townsend, N., 2016. Dental disease in aged horses and its management. Veterinary Clinics: Equine Practice, 32(2), pp.215-227.
du Toit, N. and Rucker, B.A., 2013. The gold standard of dental care: the geriatric horse. Veterinary Clinics: Equine Practice, 29(2), pp.521-527.
Du Toit, N., Burden, F.A. and Dixon, P.M., 2009. Clinical dental examinations of 357 donkeys in the UK. Part 1: prevalence of dental disorders. Equine veterinary journal, 41(4), pp.390-394.
Ireland JL, Clegg PD, McGowan CM, McKane SA, Chandler KJ and Pinchbeck GL (2012). Disease prevalence in geriatric horses in the United Kingdom: veterinary clinical assessment of 200 cases, Equine Veterinary Journal 44(1): 101-106.