Last Updated on March 18, 2022 by Allison Price
QUESTION What is “parrot mouth”, and how can it be solved?
DR. BRAD TANNER Parrot mouth refers to the position of the upper lip that is forward and lower than the lower. This is the term for horse overbite malocclusion. If the top jaw is growing faster than the lower, the front teeth will become longer and less in contact with the lower incisors. This is why you get the “parrot-mouth” look: the large, goofy lips on the top jaw.Dr. Brad Tanner
Is there a problem?
Both yes and no. It’s not only unattractive for some, but it can also affect your performance. If managed properly, it won’t. This will ensure that the horses continue to eat and grow, and they won’t become skinny from lack of exercise. This can pose a problem for horses. It is important to determine if these are the only malocclusions that are affecting the incisors. If the front teeth do not contact each other, it’s possible that the entire top jaw has shifted forward. This can cause a ripple effect. The first cheek tooth may not be grinding on the cheek tooth at the bottom. The reverse is true. The last cheek tooth on top may not be grinding on the bottom cheek tooth. This could lead to large hooks or excessive growth.This image shows the “hooks” that can appear when the top and bottom jaws don’t align properly and part of a tooth is not worn down as normal. Photo courtesy Dr. Brad Tanner
Horses can suffer severe pain and discomfort from this. Large hooks can cause collateral damage to their soft tissues, gums, cheeks, and soft tissues. The problem is exacerbated when the horse is asked to place his head in a collection or frame. This causes increased contact with the teeth and soft tissues. The effects on Thoroughbred racehorses are less severe than those in dressage or other disciplines. Racehorses tend to run on looser reins, with a longer neck and extended head than those that are in flexion.
Is it possible to correct it?
This is a permanent defect in horses but can be corrected in foals as young as three months. The ideal time to correct this condition is between four and six months of age. An orthodontic appliance with wires can be used to stop the growth of the maxilla, which is the top jaw. This will allow the mandible to catch-up. An aluminum plate is used to apply an inclined plane, allowing the lower teeth and the aluminum plate to interact with it during every chewing motion.Corrective devices can fix parrot mouth if it is caught early in a horse’s life, before skeletal development is complete. Photo courtesy Dr. Brad TannerCorrective devices can fix parrot mouth if it is caught early in a horse’s life, before skeletal development is complete. Photo courtesy Dr. Brad Tanner
After the horse’s skeletal development is complete, it is impossible to correct an overbite/parrot-mouth malocclusion.
How can you solve this problem over the long-term?
These malocclusions can be managed long-term by floating the overgrowths and decreasing their size. These are overgrowths that result from some teeth not being in occlusion or chewing together. Normaly, teeth grind and lose their shape at the same time. However, if one tooth is not in close contact with the other it can continue growing throughout the horse’s life at a rate of 3-4 millimeters per annum. This can cause serious damage to the horse’s teeth and lead to painful situations.
These types of malocclusions can often be managed long term. Routine floating examinations will be required at six-month intervals for horses with these types. These can be managed well and horses will have normal dentition. They will also perform at normal levels. The parrot mouth will not make horses run faster or slower. As long as the parrot mouth is managed well, it shouldn’t have any effect on horse performance.
For a long time, it has been questioned whether a parrot’s mouth is heritable. This trait is often considered a heritable trait and can be passed down from generation to generation. It is not desirable in breeding stock. Although much research has been done on this topic, it is clear that the heritability for overbite/parrot mouth is complex genetic trait. Recent research has shown that there are many genetic alleles involved in this defect’s expression. Because of the complex of alleles required to produce this result, it is hard to determine which foals might develop this defect and which sires are more likely to pass it on.
Parrot mouths, in summary, are not a major problem for many horses. Parrot mouths have survived for millennia in this manner and they will continue to eat, graze and survive. A mature horse with a parrot mouth can be managed well to reduce dental problems and pain. This will result in better performances at a racetrack or show ring. Recognizing a horse’s parrot mouth early allows for surgery and normal dentition throughout the horse’s lifetime.