Diastema in horses

Equine Dental column BR Farm
GAPS: Gaps visible between incisors after cleaning. (FW49-528NN)

HAVE you ever had food caught between your teeth? Most of us have and it’s a uniquely annoying and painfully distracting sensation. Horses’ teeth should be positioned closely against each other and function as a single unit in order to enable the horse to chew food comfortably and effectively. A ‘diastema’ is the name of the gap or abnormal space between teeth. If there are gaps anywhere between teeth, food will get stuck, resulting in increased pressure on the sensitive periodontal tissue.

A key difference between human and horses, apart from the fact that they can’t floss, is the amount of time spent eating. We eat on average for about an hour a day, whereas the horse will chew for up to 18 hours in the wild, increasing the quantity of food that can lodge in an equine diastema.

FOOD POCKETING: Incisor Diastema - showing extreme food pocketing. (FW49-527NN)

Diastema give rise to a host of symptoms, including water dunking feed; head nodding; bit snatching; malodourous breath and hyper-salivating, but perhaps the most common symptom is ‘quidding’. This is when the horse partially chews long-stem forage (hay/ haylage) but drops it out of the mouth without swallowing it. While some horses may subsequently re-ingest the feed most affected horses usually drop weight due to overall reduced feed intake.

Diastema are diagnosed more in the winter due to the changes in feeding regimes. Grass is much softer than hay and therefore it requires less chewing effort. The presence of greater quantities of lignin in hay/ haylage leads to a tougher stem. This in turn places greater forces on the cheek teeth, reduces the grinding efficiency and results in a bolus of food too large to safely swallow. If the horse does attempt to swallow the partially chewed hay, then they are at a higher risk of developing choke or colic due to impactions.

Horses can develop diastema as they age (geriatric diastema), or in some cases they are present from a young age (congenital diastema). Congenital diastema may be the result of displaced teeth, insufficient angulation between teeth or narrow/ missing teeth, while geriatric diastema are the result of teeth narrowing as they age. Once food fibres get caught in the narrow space, the chewing cycle pushes the fibres into the diastema towards the sensitive gum tissue. Once it reaches the gum, the horse is unable to clear it and the impacted feed will continue to track into the space between teeth resulting in a painful periodontal pocket, which can be extremely deep. In order to treat them successfully, they need to be flushed completely clean, often a difficult process, before being assessed for possible packing or widening to allow the food to be cleared more easily. No fixed treatment plan can be applied to all cases of diastema and each case is managed on an individual basis. In extreme cases, where symptoms cannot be managed with conservative treatment, extraction of displaced or misaligned teeth may be necessary in order to treat the diastema by creating a larger, more comfortable, gap instead of a small painful pocket.

While some horses have only one abnormal space, it is also not uncommon to find multiple diastemata in an individual horse. They can affect both incisors and cheek teeth, but symptoms are most commonly attributed to the cheek teeth, in particular the back three, which are impossible to see without a dental speculum, light source and mirror. Due to the painful nature of the condition, examination is best achieved in sedated horses and in particularly sensitised horses a nerve block may be the best option to facilitate treatment.

If you suspect your horse may have a problem, seek advice from a qualified dental specialist.


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