Your horse has sore teeth? – then call the equine dentist

One type affects the central area of the upper cheek teeth and is known as ‘infundibular caries’, the other causes decay on the outside of the cheek teeth and is known as ‘peripheral caries’.

This article aims to explain how this tooth decay arises, the problems it can cause and how we can treat it.

Horses have hypsodont teeth which erupt throughout their lives, whereas we have brachydont teeth. Our teeth have a crown which is completely covered in enamel.

This image is of infundibular caries where the cavity is being cleaned

In contrast, horses' cheek teeth have enamel, dentine and cementum making up the crown of the tooth. Each of these substances wear down at different rates, which helps horses to grind down forage effectively.

Enamel is the hardest part of the tooth and translucent white in appearance. Dentine is the second hardest substance and it picks up staining from feed material and therefore the surface of the teeth are shiny brown where the dentine is.

This dentine covers and protects the sensitive living pulp of the tooth from exposure at the surface. Cementum is more yellow in appearance and surrounds the outside of the teeth.

The upper cheek teeth of horses have two cone-shaped structures in them. These are blind ending cones which are surrounded by enamel and filled with cementum.

They add strength to the structure of the teeth and make the upper cheek teeth slightly wider than the lower cheek teeth, which don’t have this structure. These are called ‘infundibulum’. It is in the infundibulum where tooth decay can occur.

The cementum filling the infundibulum of the cheek teeth is normally complete before the tooth erupts. If during this time of development there are gaps in the cementum, or incomplete filling of the infundibulum, then holes are left into which food can become trapped.

This is very common in horses. In the UK, around 50% of horses have some degree of tooth decay known as infundibular caries.

The question of why so many horses have caries is yet to be answered. We know that the disease is very common and the fourth upper cheek tooth is the most frequently affected tooth.

This tooth erupts when the horse is around one and a half, therefore a lot of the development of this tooth occurs during a vulnerable time in the young horses’ life, after weaning. This may affect its development.

Studies have found there is a geographical influence on the prevalence of infundibular caries, and this may be linked to diet and water acidity. Caries develop when trapped food undergoes fermentation by bacteria, which produce acid, which erodes away the mineral content of the teeth creating cavities.

The concern with infundibular caries in horses is related to the progression of the disease which weakens the strength of the tooth. The decay can spread from the infundibulum into the surrounding enamel and dentine.

This can result in tooth root infections and fractures of the cheek teeth. This occurs slowly over several years.

The end result is a problematic fractured tooth, often accompanied by sinus infection and nasal discharge. At this stage, extraction of the tooth is required, which is inevitably difficult and also carries the risk of further complications. The cost of treatment at this stage can run upwards of £2000.

The progression of infundibular caries can be stopped by early diagnosis and treatment. Compared to 10 years ago, veterinary treatment involving filling the caries is now widely available.

Treatment involves drilling out the diseased areas of tooth and thoroughly cleaning out all the food material. In order to carry this out safely, the horse is sedated and normally standing in stocks with the head resting on a headstand.

An oral endoscope is used to help visualise the tooth being treated and ensure that the procedure is being carried out correctly. Once the cavity has been thoroughly cleaned, a filling is placed.

Stage one: This picture is of infundibular caries of a maxillary cheek tooth

The fillings used are like those used in human dentistry. In comparison to human fillings the cavities are a lot larger and harder to access! Once filled the filling remains in place very effectively and wears down at the same rate as the tooth.

Stage two: this is the same cheek tooth once the preparation process is complete and the cavity ready for placement of the filling

Most times these fillings last the lifetime of the horse and don’t need replacing. Filling infundibular caries stops the progression of the disease and prevents the tooth from fracturing down the line.

Stage three: Image is of the tooth once the filling is in place

The cost of fillings is less than the cost of dealing with a fractured tooth and can stop the tooth from requiring extraction. This is also much better for the welfare of the horse.

One of the biggest problems for horse owners is the under-detection of infundibular caries and then not having the opportunity to deal with the condition, and stop progression.

Not all caries need treating. Shallow ones and those at the early stage affecting teeth that are less susceptible to fracture can be monitored. Most horses requiring treatment are between 10 and 20 years old.

The presence of infundibular caries can easily be missed during dental treatment if the dental examination is not carried out thoroughly. All horses should be checked at least once yearly, with a speculum, bright head light and every individual tooth examined with a mirror. In most horses this requires some sedation.

The dental examination should not be under-estimated in terms of its significance. Ensure that you have a suitably qualified BAEDT registered dental technician or equine veterinarian carrying out the dental examination and treatment.

Taking an active role in ensuring your horse has a thorough dental examination is in your and your horses’ best interest. Your own vet should be able to advise you on dental fillings.