What is sow mouth in horses?

Sow mouth, also known as prognathism, is a dental abnormality from birth where the lower incisors extend beyond the uppers, creating an underbite.

The condition can range from mild to severe. Because the incisors don’t meet properly, the cheek teeth may also wear unevenly over time. This condition is believed to have a genetic component.

The biggest concern is grazing efficiency. Horses with sow mouth often struggle to bite off short grass, and in more severe cases may not be able to graze effectively at all. A constant supply of hay is essential to make sure they get enough fibre.

Sow mouth can also lead to:

Irregular wear of the cheek teeth.
Difficulty chewing and restricted jaw movement.
Pain, poor condition, or weight loss.
In some cases, discomfort that affects handling, head carriage or acceptance of a bit.

While sow mouth can’t be corrected, it can be managed. Regular dental care helps keep chewing comfortable, and a fibre-rich diet supports long-term health.

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