Teething troubles often go unnoticed in a young horse. Any problems with the growth and shedding of a youngster’s deciduous teeth (often called temporary or milk teeth) can lead to long-term issues when permanent teeth arrive, affecting not only the horse’s physical development but also his attitude towards work and his willingness to accept a bridle.
The eruption sequence (when a horse’s teeth break through the gums) is far from straightforward, with multiple deciduous and permanent teeth being present in the mouth at any one time.
Between the ages of one and five, a horse will erupt 24 permanent cheek teeth and 12 incisors — and in some cases an additional four canine teeth. Dental examinations during these years should look for a normal eruption sequence and any sources of soft tissue pain, such as cheek ulceration from sharp enamel points on the upper cheek teeth.
Mind the gap
Retained deciduous incisor tooth (white arrow)
Deciduous teeth that are about to be pushed out by their permanent counterparts are commonly known as caps.
Very worn and loose caps can cause the horse pain by pulling on the gingival tissue at the gumline. This allows food to accumulate between the cap and the permanent tooth, causing periodontal (gum) disease.
Loose caps and those packing food are easily removed with a pair of cap forceps. It is preferable to extract the contralateral (opposite) cap at the same time to allow the mouth to remain balanced.
The mouth should also be examined for the correct number of teeth and their proper positioning. This is easiest in the incisor region, where six upper and six lower incisors should be present.
When a deciduous incisor is retained, it commonly causes a lingual (towards the tongue) displacement of the permanent tooth. If the permanent incisor develops beside the deciduous incisor there will be seven in the row.
Occasionally, radiography may be required to distinguish between the two.
Retained deciduous incisors are easily removed under sedation and local anaesthetic.
Supernumerary (extra) incisors can also be present. If these are not causing major problems with contact between the upper and lower teeth, or periodontal disease, they are often best left in place.
Supernumerary cheek teeth may also emerge — most commonly at the front or back of the mouth, although occasionally in other abnormal locations. These have delayed eruption compared to other cheek teeth. Because they often have nothing opposing them, they are prone to overgrow and require regular rasping.
Abnormally shaped or misaligned supernumerary cheek teeth can pocket food, leading to periodontal disease. In such cases, removal of the extra teeth is often the best course of action — although this can be difficult, particularly at the back of the mouth.
CT scan showing a deciduous cheek tooth (red arrow) with the underlying permanent cheek tooth (blue arrow)
Two caps following removal
Dealing with diastemata
Diastemata are defined as inappropriate spaces between teeth.
They are classified as “open” where the gap is the same width at the occlusal surface (the grinding or biting face of the tooth) as at the gingival margin (the very edge of the gumline). Where the gap is smaller at the occlusal surface, they are termed “valve”.
Diastemata can be further classified. “Primary” refers to those caused by insufficient angulation of the cheek teeth, or because the dental buds (the developing teeth) are too far apart. “Secondary” describes those caused by displaced cheek teeth or large overgrowths. Both can be present in younger horses due to eruption disorders.
Misalignment of the cheek teeth may lead to diastemata. If these teeth are identified early, palliative rasping may limit further displacement and the severity of subsequent disease.
Many clinicians believe that disease due to diastemata is the most painful oral cavity disorder.
Quidding is a common clinical sign, where the horse drops semi-chewed food from his mouth. Most horses cope with eating grass and hard feed, but may struggle with long fibre and fail to maintain body condition.
The most common site for problematic diastemata is in the spaces between the rear three lower cheek teeth.
Diagnosis is made with a careful oral examination, which is greatly aided by sedation. Food is then removed from between the cheek teeth, usually with water lavage or right-angled picks.
Many treatments are available, although some are more suitable for certain cases than others.
The mainstay of treatment is high-quality rasping by a veterinary surgeon or qualified dental technician to remove transverse ridges of the surface of the teeth opposite the diastemata.
A deep periodontal pocket between teeth can be packed with dental impression compound to aid gingival healing. A small subset of diastemata can benefit from widening to make the gaps bigger, although there is potential to do serious damage to the cheek teeth.
Cases with secondary diastemata due to severely displaced cheek teeth ultimately may require removal of the offending tooth.
Treatment of diastemata cases is likely to be prolonged, with some cases requiring lifelong care.
Feeling the pinch
Two wolf teeth following removal
Wolf teeth in horses are normally positioned just in front of the first cheek teeth, but not all horses have them. Most cause no problems, but some horses experience discomfort due to pinching of the cheek onto the tooth, caused by a bridle or headcollar.
Provided they are normally positioned, wolf teeth can be removed by a vet or a qualified equine dental technician under direct and constant veterinary supervision. I would recommend the use of local anaesthetic (which must be administered by a vet), in addition to sedation.
Wolf teeth in the lower jaw, or those that are malpositioned or blindly erupted (still below the gum), generally cause problems and should be removed — a procedure that can only be carried out by a vet.
Early identification and treatment of many eruption conditions can limit their severity, so regular dental checks from yearling age onwards are recommended.
The removal of problematic wolf teeth or sharp enamel points will aid trouble-free bitting when the horse is old enough for breaking.
Ref: Horse & Hound; 7 January 2016
