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Dental Development in Young Horses

So your foal has celebrated its first birthday? Well then there are a few things you might like to know about the dental development and changes going on inside your youngster’s mouth.

The first few years in a young horse’s life are filled with change as they rapidly develop and grow, and this is also true of their head and inside their mouths.

By around four years of age, the normal horse will have at least 36 teeth, with the presence of canine teeth and wolf teeth increasing this number even further.

What’s more, during this period they will have shed (lost) 24 deciduous or baby teeth, replacing them with permanent or adult teeth.

For the yearling, this process begins with the eruption of the first molar into the mouth. Cheek teeth are divided into either premolars and molars; a premolar is a tooth where the adult tooth replaces an existing baby tooth, while a molar is a tooth that erupts for the first time as an adult tooth with no pre-existing baby tooth to replace. Therefore, of the six cheek teeth from front to back in each arcade or set, the first three are premolars, whilst the remaining three are molars.

At around 12 months the existing three deciduous premolars are joined by the first adult molar. This is part of a bigger, clever evolutionary adaption to allow tooth development to occur alongside growth of the skull. Joining molar one at around two and then three years of age consecutively, are molars two and three. At a similar time, the adult premolars also erupt, displacing the baby teeth, or “caps”.

This process of adult cheek tooth development and eruption is also the reason behind something commonly observed by owners of young horses - teething bumps or, more technically, eruption cysts. These bumps are more often visible on the lower jaw, however the process is occurring wherever an adult tooth is developing. Whilst these bumps themselves are a normal part of the teething process, problems can sometimes occur. Visible signs of this can include having one bump that is larger than the corresponding bump on the other jaw, a thickened, hot area, or the development of a hairless area or discharge.

abscessed cheek tooth in a young horse
Abscessed cheek tooth in a young horse

The roots of fractured deciduous teeth can also be retained below the level of the gum. This can go unseen for some time and will continue unresolved if not found. These retained roots cause on-going gum disease and will remain present for life if not found and removed.

Problems with tooth eruption are common

Problems with tooth eruption are common, in fact they still represent the most common presentation for tooth removal later in life. It is important to appreciate that problems at this stage of development can lead to serious consequences later. Also, more serious visible signs of the problem may not occur for several years. This is the reason why regular dental checks and seeking out the right help and advice are very important for this age group of horses.

It is also important to understand that when teeth erupt, there is obvious disruption to the surrounding gum tissue. This is referred to as eruption periodontitis. Periodontitis is the inflammation of the tissues surrounding the teeth. Normally, this process is only temporary, and the inflammation settles down in time. However, some situations can lead to the periodontitis becoming a permanent disease process, for example, retention of deciduous teeth or displacement of teeth. This is a serious problem when it occurs in very young horses and has lifelong consequences. The best defence against this is always early detection, seeking qualified help and obtaining the right advice.

retained deciduous cheek tooth with periodontal disease
Retained deciduous cheek tooth with periodontal disease

Tooth development and tooth formation

As tooth development follows a stepwise order, injuries or genetic malformations (ie mixing up of the steps involved) can result in abnormal changes to tooth formation. This can lead to a range of different problems; from the failure of teeth to form individually resulting in fewer teeth, to the splitting of developing tooth buds to form extra partial or whole teeth, through to the development of dysplastic teeth. A dysplastic tooth can be thought of as one where the right parts maybe present but not in the correct percentage, location or order - a sort of dental scrambled egg!

The rapid rate of dental growth and change in young horses can also be associated with some dental tumours. Some examples of these include odontomas and amelioblastomas.

As you can see, the dentition of young horses is complex.

About the author

Dr Shannon Lee BVSc, MANZCVSc (Eq Dent), DICEVO

Advanced Equine Dentistry

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