A horse’s teeth and jaw are always changing, especially in the early years. “A foal is born with 12 molars – the teeth at the back of his mouth – and within a week or so, the incisors, or nippers, erupt at the front. A foal’s skull is not long enough for a full set of teeth at birth, but by nine months they are all there,” says MacKinnon.
Around the foal’s first birthday, the first permanent molars erupt, and at about 30 months the baby teeth start to fall out. They are all gone by four and a half years, and all the permanent teeth are in place by age five. The full complement includes 24 molars, plus up to four “wolf teeth” (smaller, often sharp teeth which erupt in both sexes in front of the molars) and 12 incisors. Most male horses also have four canines, or what MacKinnon calls the “fighting teeth,” which are seen in about one per cent of mares as well.
Your veterinarian will likely examine a new foal’s mouth during the first physical exam shortly after birth to determine if the foal has a normal “bite.” Abnormalities such as an overbite (parrot mouth) or an underbite will need special attention as the foal grows.
MacKinnon says that when you begin regular dental checkups for your young horse depends on how the horse is fed. Horses shown at halter as foals or yearlings are often fed extra processed food so they look good in the show ring, but that can accelerate the misalignment of their teeth. A young horse who is spending much of his time at pasture may not need dental care as early. However, MacKinnon does recommend that the horse be seen by someone with expertise in dental care before the horse begins training with a bit in his mouth. “The wolf teeth should be removed, and the equine dentist can ensure the teeth are balanced before training starts,” he says. “The cost of the dental exam and treatment can pay for itself by reducing the amount of time the horse takes to train.”
For younger horses (under five years old), MacKinnon recommends a dental check-up every six months, because the teeth and jaw are changing rapidly. After that, once a year is usually sufficient unless there are problems.
Correcting uneven growth
Unlike human teeth, the horse’s permanent teeth will continue to grow throughout his life – approximately three millimetres per year. This is a very important factor in dental care, because that growth, if it is uneven or uncontrolled, can cause malocclusion (poor contact between upper and lower teeth) and pain or difficulty eating for the horse.
MacKinnon explains that wild horses in their natural habitats use their nippers (incisors) and molars about equally. They bite off pieces of grass or other plants with their front teeth and grind them with their molars, wearing all the teeth down fairly evenly as they grow, keeping everything in balance. But for the modern horse, especially in northern climates, that rarely happens. Some horses may forage on pasture four or five months out of the year in Canada, but the rest of the time they are eating hay and grain. Others spend little or no time on pasture at all and are fed mostly hay, grain, or pellets. “The horse who is eating hay is not using his nippers at all,” says MacKinnon. “But those molars are still grinding the hay, pellets or grains, so they are getting worn down.”
The result: while the molars wear down, the growth of the front teeth outpaces the amount that is worn off, causing the incisors to protrude and become misaligned. MacKinnon says that many people believe those long, protruding teeth are a natural part of equine aging, but they are not: they are simply the result of disproportionate growth of the incisors compared to the molars.
When the front teeth become too long, they can also cause a gap in the back teeth between the top and bottom molars. This leads to pain in the horse’s jaw and makes it difficult for him to grind his food effectively. It can also affect his performance when being ridden. “If his teeth are distorted, it will change how the horse carries his head and that can impede his freedom of movement,” says MacKinnon. “Imagine having pain in your jaw and then someone puts a metal bit in your mouth as well and pulls on the reins. A horse who is comfortable in his mouth is much better able to comply and move freely.”
To restore the balance in the horse’s mouth, uneven or jagged molars are filed down in a process called “floating” (image 1). The horse is restrained, his mouth is held open (usually with a full-mouth speculum) and the dentist uses a either a manual rasp or a power float to file down the teeth that are overgrown. The goal is to have all the top and bottom molars meet evenly, freeing up the horse’s jaw so that it can move in all directions and feel comfortable, while allowing the teeth to grind the food effectively.
To maintain the normal straight-up-and-down angle of the incisors, your equine dentist will remove any overgrowth with a specialized grinding tool (image 2), allowing the front teeth to meet with an even surface, and the back teeth to make proper contact. MacKinnon stresses that this attention to the incisors is a very important part of the regular dental routine to achieve full-mouth balance.
Cavities and other concerns
MacKinnon explains that while thankfully rare, horses can get cavities, as their teeth have natural folds and indentations and holes and the sugar in apples and sweet feeds can cause potential dental problems. If a tooth becomes rotten or loose it should be removed, either with the horse standing or under general anesthesia, to prevent infections or further health issues.
Be aware of signs that your horse may need a dental check-up sooner than the once-a-year schedule: a bad smell coming from his mouth; rotting, partially chewed food dropping out of his mouth; slobbering his grain; a discharge from one nostril or eye; and indications of pain or discomfort when being bridled. MacKinnon also suggests checking your horse’s manure – long pieces of grass or large amounts of intact grains can indicate that he is not grinding his food effectively.
Dental care can also be provided by veterinarians, as equine dentists, who have more training specifically in care of the teeth, are not available in all parts of the country. “Regular dental care compensates for the unnatural conditions that we keep our horses in,” says MacKinnon. “It’s an important element of health care and contributes significantly to performance.”