A horse relies heavily on its teeth to aid digestion.
The stomach acids are unable to break down the cellulose in grass, so this is done by bacteria in its colon.
If the horse's teeth are in a bad / neglected condition, then the bacteria in the horse's mouth will become ineffective.
The first or starting point of the digestive system is in the mouth, constant chewing of the grass, or hay, will break down into a form that the horse's body can successfully digest.
Again the teeth have to be cared for, to avoid colic, which is a serious condition for the horse, and can lead to premature death.
The horse's teeth in a bad condition, can also cause discomfort, when a bit is placed in the mouth and the animal can be difficult to control, when exercised.
A regular check, of the horse's mouth, by a vet is important and rasping of the teeth if necessary.
The age, can also be identified, as the teeth continue to grow through the life span of the horse.
The horse's upper and lower jaw are basically identical, as far as teeth are concerned.
The adult horse have six premolar and six molar.
These are for chewing (the start of the digestion process).
In a young horse, the three back molars on each side, upper and lower are not present.
Horses also have incisors (cutting teeth); three each side, upper and lower jaws, twelve in total.
Usually, by the time a horse reaches its fifth birthday, it will have lost all its milk teeth and have a full set of adult teeth.
Conclusion A horse's well being begins at it's mouth, if it has healthy teeth, it will be able to chew and digest food successfully, and essentially develop in ways necessary for a horse's longevity.