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How a horse eats
Equine teeth are different to those found in dogs, cats and humans. They are known as hypsodont teeth, which means they erupt continually throughout the horse's life, usually at around 2-3mm a year. Whereas with humans, cats and dogs, our teeth have little reserve crown (the tooth and root below the gumline), a young horse may have a good eight cm of reserve crown in the gum, that will gradually erupt over its life.
Horse teeth are designed like this because of their diet. The first stage of digestion in animals is mechanical - the teeth are used to physically break down the feed. In the horse's case, it begins by nipping grass with its incisors, and then uses the tongue to pass the forage back to the cheek teeth. The horse then rotates its mandible (lower jaw) in an elliptical pattern, moving down, out to the side, up and then sliding the jaw across so that the molar surfaces meet and grind the feed.
This forms a cigar-shaped wad, or bolus, of feed. The feed is passed further and further along the cheek teeth as the horse chews, getting more and more finely ground. By the time the forage reaches the very back molars, it should look very finely chopped, ready for chemical digestion by the stomach, caecum and intestines.
This constant grinding pattern has an abrasive action on the horse's teeth, especially if the horse has a diet of coarser feed such as hay, tussock etc. For this reason, horses evolved to have teeth that continuously erupt, in an effort to maintain the same amount of clinical crown (the amount of tooth visible above the gumline) at all times.
The big problem with this is that modern feeds and pasture are much softer and require less grinding, which throws this mechanism off-balance. In addition, doing things like feeding a horse off the ground also disrupts the normal grinding pattern of the horse.
This is how horses end up with uneven wear patterns, and these can show up in the mouth as high teeth, hooks and ramps on the molars, excessive ridging on the grinding surfaces of the molars, and misaligned incisors.
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Dentistry in miniature horses
Although miniature horses are often kept as companion animals rather than competition or performance horses, it is still important to consider their dental care as part of their overall wellbeing.
While a miniature horse may have a body that is quarter the size of a horse, their teeth are still usually the same size as an average horse. This means that a miniature has the same amount and size of teeth that need to fit into a much smaller space – which can lead to malocclusions (misalignment of teeth) and other dental problems such as overcrowding.
Miniature horses also often shed their deciduous teeth later than full size equines. Horses have a total of 24 deciduous teeth, and these generally shed at set times in the young horse's life, with the eruption of permanent incisors and premolars taking the place of these deciduous teeth.
Because miniatures often retain deciduous teeth longer than they should, this can cause discomfort for the horse and also can affect the eruption and positioning of permanent teeth.
The teeth are an important first step in any horse's digestion – unless a horse is able to mechanically break down forage enough by grinding it with its teeth, the rest of the digestive tract will be unable to further break the feed down and feed will pass through the horse undigested.
A horse's teeth can only grind feed effectively if the lower jaw is able to rotate around the upper jaw freely, without being blocked by malocclusions such as high teeth, ramps, hooks, or excessive ridging on the grinding surfaces of the teeth.
These problems are usually not visible from the outside – and your miniature may even be a bit overweight. However a horse with a good body condition can still have dental problems.
Because of all these factors, regular dental care of miniature horses is essential for their comfort and dental functionality. Younger horses (those under five years old), and especially younger miniatures, should have dental checks every six months, to reduce the likelihood of problems due to retained deciduous teeth. More frequent checks are also recommended in aged horses, while those between the ages of five and 20 are usually put on an annual programme.
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Bitseating
Bit seating a horse's teeth basically means rounding the front aspects of the very first upper and lower cheek teeth - so when you look at a horse's cheek teeth side-on they are rounded from the gum line down towards the back of the row of cheek teeth.
There are varying degrees of doing this - some as extreme as what's known as an Argentinian Bitseat, that rounds the entire tooth as far back as the second cheek tooth, taking most of the first cheek teeth out of occlusion (meaning they do not grind against each other), and then less extreme where the front of the tooth is rounded off, usually working on only a quarter of the grinding surface of the tooth.
Bit seats serve two purposes. Firstly, as the name suggests, they provide a space for the bit to sit. This means instead of sitting on the bars and tongue of the horse's mouth, when contact is taken up the bit will 'slot' into the small space created between the upper and lower teeth, reducing bar and tongue pressure of the bit.
With the reduced tongue pressure, the horse can relax its tongue, so that it sits flatter in the mouth and therefore improving the passage of oxygen from the nose through to the trachea (windpipe).
The more oxygen the horse can get to its lungs, the better it can perform.
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Wolf teeth
The name 'wolf tooth' is almost a bit misleading - wolf teeth are in fact remnants of a fourth premolar, from a time when horses were smaller in size and had a different diet.
Wolf teeth are found just in front of the first premolars, right about where the bit is positioned when a contact is taken up. They are sometimes confused with canine teeth - which are much larger and generally found only in stallions or geldings (although mares may have small canines present). Canines are also located more rostrally (more towards the nose of the horse) than wolf teeth, and are usually found about one-third to one-half way along the bars of the mouth.
Wolf teeth are mostly found on the upper jaw however can also be found on the lower jaw - the latter is not so common but it's also not abnormal to find lower wolf teeth.
Because wolf teeth are remnants of teeth, they are relatively small, and have shallow single roots. They can vary in size from a few millimetres in diameter to the thickness of a pencil. This is why they are a problem - their type of root means they are not as well anchored to the jaw as an upper premolar with three roots that is around 3 inches long.
When the bit comes into contact with a wolf tooth, it can cause pain and irritation to the horse. It can be likened to us trying to drink a hot or cold drink with a super sensitive tooth. This discomfort can be shown by the horse flicking its head, tilting its head (especially if the horse has a wolf tooth on only one side), rearing, bolting, coming behind the contact, snatching at the bit, and more. Because of this I recommend wolf teeth are extracted in any horse that will have a bit in its mouth.
Wolf teeth can also be blind - that is they have not erupted through the gum. However they can be palpated through the tissue, and usually feel a little loose sitting in their pocket of gum. These teeth should still be extracted, as they can still cause pain and discomfort when contact is taken up on the bit.
Wolf teeth usually erupt between the ages of 6-18 months, so it's a good idea to have your horse's teeth checked before it is mouthed. This way if the horse does have wolf teeth, they can be extracted prior to mouthing and the whole process of putting a bit in the horse's mouth will be more pleasant for the young horse.
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Power driven dentistry tools
When we talk about using power tools in equine dentistry, we're generally not talking about grabbing the Ryobi drill from the shed and using that on a horse's mouth.
The power driven dentistry equipment I use is specialist equipment, much of it developed by equine dentists who cleverly saw a gap in the market for that tool. These tools are designed to work specifically with a horse's teeth, and fit in the small spaces at the back of the mouth that can be difficult to reach.
Power tools are not as new as you might think either - there is evidence of them being used around 100 years ago, when equine dental care was in a golden age. Horses were an essential part of daily life and in many ways, horses had better dental care 100 years ago than they did 20 years ago.
However just as human dental equipment has progressed on from the treadle type contraptions that my mum used to go into a cold sweat over, so has equine dental equipment. The gear available these days is well made, and long-lasting. Power tools are also kinder to the soft tissue (gums, tongue) in the mouth than hand tools, and are less likely to cause injury.
The other big advantage is that using power tools can mean less frequent visits for your horse. The job they do lasts longer, and is more accurate. Reducing a large hook or one high tooth is a quick and easy job using power tools, that might take a minute. Reducing large hooks with hand floats can take a lot longer, causing more stress for the horse.
Common myths about power tools
Power tools take off too much tooth
A power tool, just like a hand tool, will only take off as much tooth as the user dictates. Hand tools have very sharp blades and its just as possible to take off too much tooth with a hand tool as it is with a power tool. The key is knowing how to use your tool correctly.
Power tools kill teeth
Power equipment does generate heat, and if a power tool is in the same position for a period of time (studies suggest varying times, from 30 seconds to two minutes), the tooth can be damaged. However if the tool is constantly moving, and being cooled with water, the likelihood of tooth damage is extremely unlikely. Running a power tool on one point for any period of time is generally not necessary in any case, as this will just reduce one tooth too much and create problems.
Only lazy and incompetent dentists use power tools
Using a power tool is just as hard physically as using hand tools - many of the tools need to be driven along the battery of cheek teeth, and require some amount of pressure. Dentists who use power tools work up just as much of a sweat as dentists who use hand tools!
It also takes some skill to use power tools and most dentists who use power tools all the time move on to using them after using hand tools and becoming frustrated with their limitations. There is a certain skill involved in being able to see a high point on a tooth, being able to position the power tool correctly and knowing how much pressure to apply.
If you have any other questions about power tools, please feel free to email me.
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Ageing a horse dentally
Horse’s teeth erupt gradually throughout their lives, which means that we are able to roughly estimate their age by looking at different markings and features of their teeth. This is especially useful in horses that are not branded.
This is by no means an exact science – just like people, horse teeth can vary based on genetics, diet and the environment they live in. Older horses (over 20) can be harder to age than younger horses.
When ageing a horse dentally, there are a few key things we can look at:
- Deciduous teeth vs permanent teeth – A young horse generally does not have a full set of deciduous incisors until the age of 9 months, and then will shed its deciduous teeth (baby teeth) roughly between the ages of 2 ½ - 5 years old. By looking at which deciduous teeth are still present, we can age a young horse.
- Canines – in male horses, these usually erupt around 4 ½ - 5 years old. Most mares don’t have canine teeth (as their purpose is for fighting between stallions in the wild), so this isn’t a reliable indicator for ageing mares.
- Cups (infundibulum) – these are small shallow cup-like indents on the grinding surfaces of the incisors. They generally begin to wear away from around the age of 6 from the lower central incisors, followed by the middle lower incisors, outer lower incisors and so on, through the upper incisors. By the time a horse is 12, you would not expect to see any cups on the grinding surfaces of the incisors.
- Dental star – this is a small mark (and is sometimes just called a “mark”) that appears on the grinding surface of the incisors. It is located above the very top of the pulp chamber that contains nerves and blood supply. It appears around the age of 8 on the lower central incisors, and just like the cups, works its way along to the middle, and outer lower incisors before appearing on the upper incisors. A 13 year old horse should have all dental stars present.
- Enamel spot – this spot marks the end of the cup, or infundibulum, and disappears from the lower central incisors around the age of 15 and progresses through the incisors in the same pattern as the cups and dental star. A 20 year old horse should no longer have any enamel spots present.
- Galvayne’s Groove – named after horse trainer Sydney Galvayne, who identified this groove in the 1800s, the groove begins to appear on the upper corner incisors, at the gumline, from around the age of 10. By the time the horse is 15 the groove is about halfway down the tooth, at the age of 20 it is all the way down the tooth, at age 25 it is only on the bottom half of the tooth and by the time the horse is 30 it should have disappeared altogether.
- Molars – the molars don’t tend to tell us as much about a horse’s age as the incisors do. All permanent molars should have erupted by the time the horse is around 3 ½ - 4 years old. After this – the next significant age marker is when the oldest teeth in a horse’s head – the first molars, which are halfway along the cheek teeth – begin to expire. These teeth are generally said to begin expiring between 18-20 years old but in practice, I have seen it vary a lot between horses and can be seen as early as 18 years old, or not until around 25-26 years old.
Looking at all of these age indicators as a whole, can help paint a picture of how old a horse is dentally – it’s important to remember though that the dental age of a horse may vary a little compared with it’s actual age. Often we can only provide a range, so for example, we might say that the horse is between 10 – 13 years old.
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