Pony Want a Cracker? – A Look at the Equine Parrot Mouth

A look at the equine parrot mouth - Oh No There's Flowers
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Equine Parrot Mouth - Oh No There's Flowers
The photo on the left is  a normal horse. The photo on the right, is Leo. Yep, my Leo.

Welcome to the wonderful world of an equine parrot mouth.*

A.K.A. brachygnathism, overshot maxilla, buck tooth, overbite, and “Holy S*@!, what’s wrong with his teeth?” Basically, an equine parrot mouth is just an overbite. It can be slight or severe and affects 2-5% of all horses. If you think about it, that means if your facility had 100 horses, 2-5 of them would have some level of parrot mouth!

Horse Skull, Equine Parrot Mouth - Oh No There's Flowers
Courtesy of Texas Equine Dentist

You see, in a normal equine mouth the front teeth (incisors) should line up perfectly. A horse’s built in pair of lawn mowers. But for parrot mouthed horses this isn’t the case.

In the slight cases the upper jaw (maxilla) sits a little bit ahead of the the lower jaw (mandible). The top and bottom front teeth (incisors) will still touch and can function reasonably well.

In the severe cases the top and bottom incisors don’t match up at all affecting total mouth function. You’re left with a majorly buck toothed horse. As is the case with my majestic OTTB.

When a parrot mouth forms it presents itself between 1 and 6 months of age. Although it can be caused by an upper jaw (maxilla) that is too long, it is most often caused by a lower jaw (mandible) that is too short.

If your horse has a parrot mouth it could be caused by a variety different reasons like genetics, injury, foal illness etc. But, surprisingly, it is not necessarily because he inherited it from one of his parents. Research has shown that parrot mouthed dams and sires show no connection to producing parrot mouthed offspring. So if a parrot mouthed horse is bred, it does not mean that their offspring will have one too (Parrot mouths are likely caused by poor dam and sire match up, however, so researchers warn to breed responsibly!).

Wait, so what does having an equine parrot mouth mean?

Whatever the cause of the equine parrot mouth, if left untreated it can cause pain and premature death in the horse. So, buckle up because it’s about to get technical in here:

Malocclusions in an equine can cause significant stress to their digestive system, asymmetrical wear to hypsodont teeth, pain and restriction during mastication, and premature death. 

In layman’s terms? There are a few things about a horse’s dental anatomy that make an equine parrot mouth problematic.

  1. Hypsodont Teeth

    Side view of Hypsodont Teeth. Courtesy of Liyou, 2005.

    Horse teeth are seriously long! They extend up into the jaw and continually erupt or “grow” throughout the horse’s life. Having these “growing,” hypsodont teeth is great due to the fact horse’s wear their teeth down with a roughage diet. The problem comes when the grinding surface (table) of the teeth don’t line up. An unopposed tooth will continually erupt and dig into the opposite gum line. In severe parrot moth cases (just like Leo) The upper incisors will grow down into the bottom of the mouth. The bottom incisors will erupt upwards colliding with the horse’s palate. These super long teeth can rub gums causing irritation, scar tissue, and a restriction of natural jaw movement.

  2. Rostro Caudal and Lateral Movement

    Rostro Caudal Movement is the natural back and forth sliding of a horse’s lower jaw bone. Lateral movement is the side to side motion we all see when our horse is chomping down on his favorite snack. Both are essential to proper chewing (mastication) as well as comfort and suppleness on the bit. In parrot mouthed horses their abnormal bite can restrict this movement, causing pain, discomfort, and difficulty training. If anyone has ever heard the term TMJ (Temporomandibular joint)  it refers to the jaw joint (humans have one too) and is known to carry a fair amount of tension in parrot mouthed horses. Definitely not fun for the horse!

  3. Hooks, and Ulcers, and Ramps, Oh My!

    With a well aligned mouth the top teeth will wear evenly on the bottom teeth and vice versa. So, our parrot mouthed equines have a bit of a harder time keeping their pearly whites in good condition. Their abnormal teeth arrangement causes uneven wearing which can lead to sharp teeth hooks and points that dig into the horse’s gums and tongue. Prolonged rubbing can cause open wounds and ulcers on the horse’s cheeks and tongue (if you’ve had braces you know the feeling. Ouch!).

    Courtesy of Liyou, 2005

    Periodontal disease (gum disease) is also a concern with an equine parrot mouth. Again, due to the abnormal teeth arrangement, the teeth can sometimes be pushed out of position creating small gaps during normal chewing. Food then is trapped between the teeth and will rot if not treated (think a popcorn kernel jammed in between your molar). Horses can abscess, as well as loose teeth due to periodontal disease.

  4. Chew and Swallow

    When your horse has a parrot mouth chewing and swallowing may be easier said than done. The misalignment of the upper and lower jaw (maxilla and mandible) can make chewing a total chore. Parrot mouthed horses may be seen dribbling their grain, wasting hay, or only chewing out of one side of their mouth due to pain related to hooks and ulcers.

    Grazing is also difficult for obvious reasons. The incisors act like a pair of scissors, cutting grass for eating. When they don’t line up a horse has a fairly hard time pinching off those short blades in late summer. For Leo, he seems to have adjusted well to having such badly aligned incisors. After all he has had those teeth for his entire life! What I notice is he definitely seems to pull up large clumps of dirt with his grass more often than other horses.

Caring For an Equine Parrot Mouth

There are a few different options for treating a parrot mouth from simple floating to corrective surgery. In the case of corrective surgery it is usually only an option for very young horses who’s jaws are still developing. Surgery is expensive and is long term since you are treating a horse as their jaw develops.

From the three veterinarians who have worked on Leo, they have all suggested the same thing – frequent, high quality, and regular dental work. Simply staying ahead of long incisors, large hooks, and nasty cheek ulcers works wonders in keeping your parrot mouthed horse pain free. A dental check at least every 6 months is a good place to start. Speak with your veterinarian to develop a dental plan that works for your horse.


Parrot Mouth - Oh No There's Flowers
Leo’s Semi Annual Dental Work

In Leo’s case his severe parrot mouth has been easier than I thought to handle. He was only four when he started getting dental work with me, so his mouth hadn’t gone through long years of unattended torture yet! Leo is on a 2x/year floating schedule which is much more traumatic for my wallet than it is for his teeth. He rides well in a simple french link snaffle and based on his chubby ribs has no problem eating. Although my veterinarian feels confident we are getting Leo on a great dental program we are constantly double checking that his parrot mouth does not get out of hand.

Does your horse have a parrot mouth too? Share the photo on the Oh No There’s Flowers FB page. And as always please share this post on Facebook, Pintrest, and with family and friends.

Happy Trails,

Equine Parrot Mouth - The Oh No There's Flowers Blog

 

 

 

 

*References:

  1. Liyou, O., DVM. (2005). Parrot Mouth in Horses. Retrieved February 19, 2017, from http://evds.net.au/article_parrot_mouth.php. Originally published in the Australian Stock Horse Journal March-April and May-June 2005
  2. Easley, J., DVM. (2012). Equine Orthodontic Techniques for Management of Incisor Malocclusion . Retrieved February 19, 2017, from https://www.acvs.org/files/proceedings/2012/data/papers/151.pdf

 

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