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A Closer Look at Horses Teeth

Feature written by British Horse Feeds consultant nutritionist, Dr Tom Shurlock.

It may not come as much of a surprise, but equine dental health takes up about 10% of veterinary practice time and is the third most common medical problem in large animal practice. Although more common, it is not exclusive to stabled horses, but they are more susceptible to most of the common problems, with the exception of sharp enamel points (SEPs) on cheek teeth. Having said that, and assuming regular dentistry work can maintain optimal dental health, there will be times when dentition is compromised, and this can impact not only on oral health but the whole process of digestion and nutrient absorption.

Whilst PETs are relatively common, but luckily easy to rectify with regular maintenance, there is a whole range of other dental problems. These can be broadly divided into overgrowths, uneven growth, ridging, slanting & curvature, as well as peridontal disease such as gum disease, abscess & gingivitis. Additionally, tooth loss can influence this list of tooth problems by modifying the growth of the surrounding area. And, although it is not surprising, this catalogue of disorders is seen more in older and veteran horses.

Whatever the underlying reason, compromised dentition can have a far-reaching effect. Affecting the ability of the horse to chew has a direct influence on the subsequent digestion of feed, even if there is material substitution for softer options in the diet.
The natural diet of the horse is grass, historically (before modern domestication) a coarser version of current species, supplemented with a range of other plant materials. Under normal feeding behaviour, a horse will nip off short lengths of the grass tips and this is relatively easy to chew. Stabled horse, on the other hand, being fed longer lengths of hay necessitate more chewing. Either way forage is a fibrous product, and the role of chewing is to prepare it for subsequent digestion. The mechanical action crushes fibre, disrupts the cell wall coats and, very importantly, drives saliva into the matrix. This bolus, when swallowed, contains broken cell walls that allows the stomach’s secretions – acid and some enzymes – to start the breakdown of feed components into absorbable nutrients. This system, because of the trickle feeding system, means there is a constant flow of feed that absorbs and buffers the acid in the stomach. Following on, a less acidic chyme enters the small intestine and the acidity along the whole length of the intestinal tract is optimised. The microbiome is suited to a less acidic environment and that ensures the best fermentative capability and generation of slow release energy.

When teeth are compromised this process is also compromised. There is less cell wall disruption, less salivary action, and the bolus is less able to mop up and neutralise stomach acid, less able to absorb gastric enzymes. Free acid may circulate the stomach, which may contribute to ulceration, and may be released into the small intestine. At the same time protein and any starch & sugar present may not be fully prepared for subsequent small intestine digestion, compounded by a possible change in environmental conditions. This in turn may affect the microbiome, further impacting on hind gut fermentation. In short, problems with chewing, due to poor dentition, can lead to gut problems; a worst case scenario, with poorly chewed long fibre, could be colic.
Obviously, the responsible horse owner avoids these situations by monitoring their horse’s mouths, feeding habits & veterinary consults, so teeth are as fit as they can be. But there are situations, such as tooth loss and old age where a horse is not as capable as chewing fibre rich feed as before and where we need to make adjustments.

The first option has long been feeding chopped forage. While this does avoid the risk of ingesting long lengths and, to a certain extent improves the salivary penetration of the short fibre, compromised chewing may not prepare the bolus sufficiently for the stomach. Another route has been replacing a portion of the forage with a more easily digested energy source, such as a cereal, or oil-based, feed. Whilst this can work on a nutrient basis, and these feeds need less chewing, both these and short chopped forages, have low acid binding capacity. So, although we may be supplying a correct energy/nutrient profile, the excess stomach acid is not utilised to prep the bolus, stomach acidity levels could be too high and subsequent gut environments changed. This leads to a less than optimal digestive process and could impact on the horse’s health and wellbeing.

Processing fibre sources can be employed as an aid to feeding dentally compromised horses. Trial work had shown that feeding rate is reduced with age and, in a specific trial, Fibre-Beet was shown not to be so strongly affected when compared to hay, and some commercial fibre feeds. This can be explained several ways.

Firstly, Fibre-Beet contains Speedi-Beet. Speedi-Beet is beet pulp that is heat/moisture treated to improve soak-ability. It also causes the disruption of the fibrous cell wall, allowing easy access of moisture into its core. This would also hold true for saliva; so, in essence Speedi-Beet is pre-chewed. Secondly, the fibre profile of beet pulp is prebiotic in nature; by including beet pulp in the diet fibre fermentation can be enhanced and the profile of the slow release energy optimal for gut performance. Thirdly, the acid binding capacity of beet pulp is high and so there is less free stomach acid to disrupt digestion. And fourthly, the fibre digestibility is high compared to forage fibre, so helps support the general decline in intake with age.

Fibre-Beet adds another level to this. Alfalfa has a very high acid binding capacity and the combination of Speedi-Beet and alfalfa improves on the physical properties of Speedi-Beet. Feeding a processed super fibre offsets the decreased chewing of a compromised or veteran horse, without disrupting the gut process that poorly chewed forage fibre would.
 
For further information on Speedi-Beet or Fibre-Beet contact a member of the team on 01765 680300.