Oral Cavity Examination - Donkey
Due to a combination of factors, including the limited angle of opening to the mouth, the rostral positioning of the lip commisures (corners), and the length of their dental arcades, it is extremely difficult to visually examine the cheek teeth, particularly the caudal (back) cheek teeth. Palpation through the cheeks may reveal food pocketing or major irregularities (such as a missing tooth or a large overgrowth) of the cheek teeth, particularly of the front three to four upper cheek teeth. Even if no abnormality is palpated, the presence of pain (i.e. the donkey pulling away or flinching) during this procedure usually indicates the presence of sharp enamel overgrowths on the outside of the upper cheek teeth. Donkeys may show visibly restricted mandibular movements that may even be confined to one side of the mouth. By fixing the upper jaw with one hand, the degree of sideways mandibular movement and the animal’s response to this manipulation can be manually and visually assessed.
It is impossible (and also dangerous) to fully examine a donkey’s mouth without the use of a gag (speculum). It is no longer acceptable to try and examine the entire mouth simply by manipulating the tongue, as suggested in texts elsewhere, as this may result in trauma to the tongue and will not allow a reasonable dental examination. For reasons of safety, a minority of donkeys need to be sedated for dental examination. Repeat examinations can often be performed without sedation in donkeys once they realise that the use of a gag is not painful. Gags are available in various types and sizes, with ‘Hausmann’ type pony-sized gags being a correct fit for the average adult donkey.
Initially, most donkeys can be examined safely using a gag without sedation. If using sedation, the dosage rates for a donkey will generally be higher than expected for a horse of similar weight. Once the gag is in place, pushing the thumb off the hard palate will usually cause the donkey to open its mouth further. Food retained in the oral cavity (which further retards visual examination) can be removed by flushing the oral cavity with large syringes of water (or very dilute disinfectant) or, failing that, by manual removal of large food accumulations and later flushing.
The use of a headlight (a penlight torch is much less satisfactory), a dental mirror, a long metal rod or ‘toothpick’ and a specialised metal basket can greatly facilitate visual examination of the equine mouth. Nevertheless, major problems, especially of the caudal upper and lower cheek teeth and of the adjacent periodontal membranes and gums, can easily be missed unless all the teeth and adjacent soft tissues (gums) are carefully palpated or a dental mirror is used. It is also useful to smell one’s hand after oral examination for the presence of foul odours which usually indicates anaerobic infections, most commonly of the periodontal ligaments but also of the teeth themselves.
Occasionally cheek teeth disorders, especially in younger donkeys, are due to localised periapical (tooth root area) abscessation which is usually accompanied by infection of the supporting bones. In most of these cases, little change is visible on oral examination of the clinical crown (the exposed part of the tooth in the mouth), unless these apical infections are very longstanding and the infection has spread to the erupted part of the tooth, or the infection has arisen following tooth fracture and subsequent exposure of the pulp. However, with training, careful examination of the occlusal surface of suspect teeth using a mirror and a fine dental probe will reveal areas of pulpar exposure in many cases of apical infection. Radiography is essential in the investigation of such disorders.
References
- Dacre, I., Dixon, P. and Gosden, L. (2008) Dental problems In Svendsen, E.D., Duncan, J. and Hadrill, D. (2008) The Professional Handbook of the Donkey, 4th edition, Whittet Books, Chapter 5
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