Genetic Test for "Sow Mouth"?

Q.  I read the article "Orthodontics for Horses," authored by David O. Klugh, DVM, FAVD/Equine. In regard to the Class III malocclusion (the lower jaw is longer and teeth are not in a position of normal occlusion), he mentions that this can be either hereditary or a delayed growth of the upper jaw. Is there a genetic test to find out if my horse's "sow mouth" is hereditary or a growth problem? Any help in this matter is greatly appreciated.

Lisa H, via e-mail

A. The simple answer is that there is not a test to determine the genetics of this condition. Unfortunately, the only way I know to make this determination is to address the orthodontic problem as early in the horse's life as possible, so as to allow maximal growth to occur. Maintain correction as long as necessary and await results. If correction does not occur, it would be wise to refrain from breeding the animal. I know this isn’t what you want to hear, but it is the state of the art as of now.

About the Author

David O. Klugh, DVM, FAVD/Equine

David O. Klugh, DVM, FAVD/Equine, is the only Equine Fellow of the Academy of Veterinary Dentistry (, a credentialing organization for veterinarians. He is affiliated primarily with columbia Equine Hospital () in Gresham, Ore.