What happens to your horse's teeth as he gets older

And how to help your senior horse maintain health & condition

Skull of a colt, 21 years old, sculptured to show embedded parts of teeth.

Both permanent and deciduous cheek teeth are shown. I 1 = first permanent incisor.

Di 2 and D 33 are second and third deciduous incisors. Dc = deciduous canine.

C= permanent canine. P 1 = first premolar ("wolf-tooth"). 1, 2, and 3 are deciduous

premolars. P 2 = first permanent premolar. M 1 = first molar.

Notice how close the upper molar teeth are to the eye socket and the maxillary sinuses.

It’s a common misconception that horses have bottomless teeth. In reality, horses are born with a finite amount of tooth length, and the way those sockets (alveoli) change over time is a fascinating act of biological engineering.

Here is what happens as a horse ages:

1. Continuous eruption

Horses have hypsodont teeth, meaning they have extremely long crowns (up to 4–5 inches) hidden beneath the gumline.  This means that in younger horses, under about 8 or 9 years, the upper molars reach almost to the eye sockets!

• Rubbing their eye could actually be due to dental pain!

• The Process: As the horse chews abrasive forage, the chewing surface wears down. To compensate, the tooth "erupts" (pushes out) at a rate of about 2–3mm per year.
• The Socket: As the tooth moves upward, the dental alveolus (the bony socket) doesn't just stay empty. It begins to fill in from the bottom with new bone.

2. Bone remodeling

The empty space left behind at the root is reclaimed by the jaw.

• Filling the Gap: As the tooth migrates toward the mouth, the body deposits alveolar bone at the base of the socket.
• Sinus Changes: In the upper jaw, the roots of the cheek teeth actually sit inside the maxillary sinuses. As the horse gets older and the teeth erupt, the sinuses actually become larger because there is less tooth structure occupying that space.

3. The 'gummy' stage

Eventually, the 'reserve' crown runs out. This usually happens when a horse is in its late 20s or early 30s.

• Shallowing Sockets: The alveoli become very shallow because there is almost no tooth left to hold.
• Tooth Loss: At this stage, the remaining nub of the tooth (the senile stump) loses its grip in the shallow socket and often falls out or becomes loose.
• Gingival Recessions: The gums may recede, and the bone underneath smooths over, leading to what horsemen call a 'smooth mouth'.

• You can roughly estimate a horse's age by looking at the angle of their incisors. As the teeth erupt and the sockets change, the profile of the teeth shifts from vertical to a much more acute, protruding angle
  

Why This Matters for Senior Horses

Food impaction and 'quidding'

As the teeth erupt and the sockets become shallow, the teeth themselves often become narrower and smaller (since horse teeth are slightly tapered).

• The Problem: This creates gaps (diastemata) between the teeth.
• The Result: Chewed grass and hay get packed into these gaps. Because the sockets are shallow, this trapped food can quickly cause periodontal disease:
• Inflammation of the remaining socket, which can then track directly into the enlarged maxillary sinus.
• Infection: Bacteria can travel down the shallowing alveolus into the jawbone.
• Signs of a problem:

• You might notice the horse 'quidding' - dropping partially chewed clumps of hay.

• Nasal discharge that is often thick & creamy or even discoloured by active infection.
  

Signs to watch out for in a senior horse

Since dental and sinus issues in senior horses are often 'silent' until they become quite advanced, spotting these subtle shifts early can save your horse a lot of discomfort.

Here is a checklist of signs that may indicate the shallowing of dental sockets or sinus enlargement is causing trouble:

1. Nasal Signs

• One-sided discharge: Is there mucus coming from only one nostril? If it’s thick, yellow/green, or persistent, it’s likely a sinus issue.
• Smell: This is the most distinct sign. Sinusitis caused by dental decay has a foul, rotting odor that you can smell even from a few feet away.
• Airflow: Check if the horse can breathe equally well through both nostrils by feeling for 'puffs' on your hand.

2. Eating Behaviors

• Quidding: Do you see 'cigars' of wet, chewed hay dropped on the ground or in the water bucket? This happens when gaps (diastemata) between teeth make chewing painful.
• Slow eating: Does the horse take much longer to finish their grain than they used to?
• Tilted head: Does the horse tilt their head to one side while chewing? This is often an attempt to move food away from a painful, shallow socket.
• Dunking hay: Some seniors start 'souping' their hay in the water bucket to soften it because their teeth can no longer handle the mechanical pressure of dry forage.

3. Physical Changes to the Face

• Facial asymmetry: Stand directly in front of your horse and look down the bridge of the nose. Does one side of the face look slightly fuller or bulged?
• Swollen lymph nodes: Feel under the jaw (the intermandibular space). Enlarged, firm 'marbles' there often indicate the body is fighting a chronic oral or sinus infection.
• Sensitivity to touch: Does the horse pull away when you brush or touch their cheek/upper jaw area?
• Rubbing their face: Does your horse try to rub his cheek on you? Or are there scraped areas where he's been rubbing on a tree or the stable?

4. General Condition

• Weight loss: Even with plenty of food, a horse with dental/sinus pain will lose condition because they aren't grinding their food efficiently for digestion.
• Whole oats/grains in dropping: Check the dropping. If you see whole, undigested grains or long stems of hay, it means the teeth have run out of grinding surface (the 'smooth mouth' stage).
  

Managing your older horse

Free access to pasture is often the best mental health therapy for an older horse, but from a purely nutritional standpoint, it is rarely enough to sustain them once their dental sockets have shallowed or they have a "smooth mouth."

The answer depends on which teeth are most affected by age:

1. If they have missing incisors (front teeth)

• The Struggle: Incisors are the "clippers." If these are missing or angled too sharply (as they often are in seniors), the horse can't "grip and rip" short grass.
• The Solution: They do much better on mid-length, lush grass (4–6 inches) that they can pull into their mouth using their lips and tongue rather than clipping it with teeth. They will struggle on a tightly mown or overgrazed pasture.

2. If they have missing molars (back teeth)

• The Struggle: Even if they can rip the grass, they can't grind it. This is where the risk of choke or impaction colic becomes high. If you see your horse "quidding" (dropping green wads of chewed grass), they are not getting the nutrition from the pasture.
• The Risk: Swallowing unchewed grass "plugs" can lead to life-threatening blockages.
• The Solution: Pasture should be for entertainment and fiber only. You must assume they are getting zero calories from the grass and provide the full 100% of their nutritional needs via soaked feeds.

3. Fresh Grass vs. Hay

• Grass is much easier: Fresh grass is about 80% water and much softer than dried hay. Many senior horses who can no longer chew hay can still manage to "gum" soft, young spring grass.
• The Vitamin Boost: Fresh pasture is a powerhouse of vitamins A and E, plus omega-3 fatty acids, which are lost when grass is dried into hay. This is great for an older horse's immune system.



4. Turnout is Vital: 

• The movement keeps their joints from stiffening (osteoarthritis) and helps their digestive tract stay "moving" to prevent gas colic.

• But, don't rely on the pasture for feed:
• if a horse can't chew the grass, they are effectively starving while standing in a green field. This leads to rapid loss of condition and even gastric ulcers.

• N.B. Seniors can get bullied away from the best patches of grass. Ensure they have a quiet area where they can graze without competition.

Is my senior horse actually eating the grass?

• The Manure Test: Is the manure formed into normal balls, or is it loose and full of long, unchewed blades of grass? (If it's long blades, they aren't digesting it).
• The Quid Check: Look for "green cigars" on the ground.
• Body Condition: Is the horse losing weight despite being on "good grass"?

Feed Preparation Guidelines

• Consistency: The mash should be wet enough that the horse doesn't have to "chew" it, but can essentially "slurp" it. This prevents choke, which is a high risk for horses with poor teeth.
• Temperature: Use warm water (not boiling) to help the pellets break down faster and make the meal more palatable, especially in winter.
• Frequency: Because their stomach is small and they can no longer graze 24/7, you should ideally feed this mash in 3 to 4 smaller meals per day rather than two large ones.

• The "Separate Table": If your senior lives with other horses, they will be the slowest eater in the field. You mustseparate them during mealtime so others don't steal their mash. It may take a senior 45 minutes to finish a meal that a younger horse would bolt in 5.
• Hydration: Senior horses with shallow dental sockets often drink less because cold water can hurt their sensitive teeth. The mash helps keep them hydrated, but always provide tempered water if possible.
• Salt: Add a tablespoon of loose salt to the mash to encourage them to keep drinking from their bucket.

• Warning: Never give a "smooth mouth" horse chaff or 'chop'.  They will try to eat it, but they can't grind it. This leads to impaction colic, as the unchewed long fibers get stuck in the digestive tract.
  

How does dental care differ for older horses?

• Over about 18 years old, a biannual dental exam is much better than a yearly one. Because the sockets are shallow, a tooth can go from "slightly loose" to "severely infected" much faster than in a younger horse.

Rasping (or floating) teeth in a senior horse is rather different to with a young horse. In a young horse, the goal is often correction (shaping the teeth); in a senior, because the dental alveoli are shallow and the teeth are short, the goal is preservation.

1. Less is more"

In a young horse, an equine dentist can be relatively bold in removing sharp points. In a senior, the mantra is "do the least amount necessary."

• The Risk: If you file a senior tooth too aggressively, you risk making it so short that the horse can no longer grind forage at all.
• The Goal: Just take off the 'razor edges' that might be cutting the cheeks or tongue. You aren't trying to make the teeth look perfect; you’re just making them comfortable.

2. Managing Loose Teeth

Since the sockets (alveoli) are shallow, teeth can become wobbly.

• Young Horse: Teeth are anchored like fence posts deep in the ground.
• Senior Horse: Teeth are more like a loose brick in a wall.
• The Difference: A dentist must be extremely careful not to accidentally dislodge or loosen a tooth further with the power float. If a tooth is already 'expired' (lost its attachment to the bone), it is often better to extract it to prevent a sinus infection.

3. Dealing with 'wave mouth'

Over time, horse teeth can wear unevenly, creating a 'wave' shape where some teeth are high and others are worn down to the gumline.

• Young horse: You can often level a wave over several years.
• Senior horse: You cannot fix a severe wave. If you try to grind down the high teeth to match the low ones, you might expose the pulp (the nerve) of the tooth because there isn't enough reserve crown left. You simply smooth the edges of the 'highs' and leave the rest alone.

4. Focus on the Gaps (Diastemata)

For seniors, the most important part of the dental visit isn't the grinding—it's the cleaning.

• Because the teeth are narrower and the sockets shallower, food gets packed between teeth and forced into the gums.
• The dentist will spend more time using pressurized water and special picks to clear out rotting forage. If left alone, this packed food causes "periodontal pockets" that lead straight to the bone infections we discussed earlier.