Category Archives: Conformation

Jaw Conformation

Horse Resource Network will be doing a series on conformational flaws to look out for when buying or breeding horses.  Our goal with this series is to explain what each flaw is and how it can affect the horse’s rideability.

We’re going to work our way systematically through the parts of the horse, starting with the conformation of the jaw.

There are a few different malformations of the jaw to look out for, including: parrot mouth (overbite), sow mouth (underbite) and shear mouth (narrow lower jaw).  Each of these flaws are hereditary. As such, horses with jaw issues are generally advised against for breeding.

Parrot Mouth: Lower jaw is too short, upper teeth protrude forward

Sow Mouth: (aka monkey mouth) is the opposite of parrot mouth, with the lower jaw protruding past the upper.

Shear Mouth: Lower jaw is narrower than upper – molars do not meet squarely.

Each of these malformations prevents the horses teeth from lining up properly (malocclusion) which may cause ridges/ledges to develop on the misaligned teeth.  These ridges/ledges can cut the tongue or the inside of the mouth which may lead to infection and/or abscesses. 

Malocclusions may also lead to interference with the natural movement of the horse’s jawbone which, in turn, may cause pain in the temporomandibular joint.  Because of the way horses are built, pain in this area may cause flexion problems.

The negative effects of these flaws can be mitigated through proper and regular dental care (which for most horses, even without these issues, should be done at least annually).  This is especially important in the case of shear mouth wherein, if left unattended, continual grinding will wear the teeth at an angle until eventually they just slide off each other, making it impossible for the horse to properly chew his food.

If you’ve owned or leased a horse with any of these issues, please comment and let us know how you dealt with it and how it affected your horses performance.


Posted by on September 14, 2011 in Conformation


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