Parrot Mouth

Several equine dental malocclusions are of clinical significance.  One of the more common is referred to as “parrot mouth”.  In most cases, parrot mouth is a congenital abnormality where the lower jaw is shorter than the upper jaw.  The upper and lower incisor teeth are not in occlusal contact in more severe cases.  The protrusion of the upper incisor teeth in front of the lower incisor teeth is referred to as an “overjet”.  The occlusal overlap caused by the upper incisors dropping in front of the lower incisors is referred to as an “overbite”. This type of malocclusion is seen in humans and most species of animals and is thought to be a complex genetic problem.  However, there are cases associated with other congenital defects and occasionally secondary to trauma in a young horse while the mandible is still growing.

The severity of the parrot mouth condition varies greatly between affected horses. Horses with a minor amount of overjet (less than 8 mms and no overbite) have fewer clinical problems.  More severe overjets have no occlusion between the upper and lower incisors. They develop an overbite as the upper incisors elongate and the upper portion of the premaxillary bone curves downward. Such movement traps the lower jaw and prevents it from growing forward at a normal rate; thus, worsening the condition as the horse ages.

The parrot mouth malocclusion is more commonly associated with the incisor teeth but can also involve the cheek teeth.  If such is the case, affected horses will develop more abnormal occlusal wear patterns as they age.

In young foals, this condition can be diagnosed soon after birth and if caught before 6 months of age, functional orthodontics can be utilized to improve or possibly correct the malocclusion.  Correction involves the application of a bite plate and orthodontic wires with the foal under general anesthesia.  This device will correct both the overbite and overjet at a rate of about 4-5 mm every 3-4 months. Most foals that have a severe parrot mouth, usually take between 9-12 months to have the optimal correction.  This may entail the application of 2-4 appliances during the 9-12 month period of time.  Foals can still suckle the mare and eat normally with the orthodontic appliance in place.  These young horses historically grow and mature normally with very few complications.

During the past 20 years, our team has treated over 200 foals with the parrot mouth condition.  We have experienced very good results and have had a high owner satisfaction rate.  If you have a foal with this condition, please contact us as soon after diagnosis as possible.  We can discuss an individualized treatment plan and address any further questions you might have.

Monkey Mouth

A “monkey mouth” is a the opposite of a '“parrot mouth. The lower jaw extends beyond the upper jaw and if there is no occlusal contact, the upper incisors become trapped behind the lower incisors. If started early enough, an orthodontic device may help improve the bite so that the upper and lower incisors wear down at appropriate rates and do not restrict movement of the mandible. As with parrot mouths, multiple appliances may be needed for 12-16 months to show the most correction.

Wry Nose

The “wry nose” malocclusion is infrequently seen. It can be congenital (born with it) or acquired due to trauma. Like the other malocclusions, the heritability of congenital cases is unknown. Despite the deviation of the nose, these foals initially do well as long as they do not have any other congenital abnormalities. However, as they grow older, the deviation worsens because the bones on the concave side of the face do not lengthen.

Generally between 6-12 months of age the deviation becomes severe enough that the airflow on the convex side (long side) of the nose is restricted by the deviated nasal septum. Since horses or obligate nasal breathers, this greatly impacts a horse’s quality of life.

The goal of treatment is to improve the ability to breathe as well as provide better occlusion between the incisors so that the growing facial bones continue to develop more symmetrically. Treatment for correcting a “wry nose” horse involves removing the nasal septum and straightening both the nasal and maxillary bones.

The bones are cut and then pinned and plated in the best possible alignment. Once the bones have healed, the plates and pins are removed. Horses that have undergone this surgery have gone on to be both riding and racehorses.