Brachygnathia in horses: 20 cases (1979-1989).

The medical records of 20 horses admitted to the veterinary medical center with a diagnosis of brachygnathia over a 10-year period (1979 to 1989) were reviewed. The study included 18 foals and 2 adult horses. Males were affected 5.7 times more frequently than females. The amount of disparity between the mandible and premaxilla varied between 0.75 and 3 cm. Sixteen foals were treated surgically with the temporary application of premaxillary tension band devices. Thirteen of the 16 surgical cases were available for follow-up evaluation. All of the surgically treated animals had improved incisive occlusion, and 6 foals had complete resolution of the deformity with corrections ranging from 0.75 to 2.5 cm. Complete correction of the malocclusion was more likely to occur if foals were treated when they were less than or equal to 6 months old. The average amount of correction achieved in foals treated when they were less than or equal to 6 months old was 1.5 cm. (range, 0.75 to 2.5 cm). Foals treated, when they were 7 to 12 months old, had an average of 0.6 cm of reduction in the malocclusion (range, 0.25 to 1 cm). Implant failure was the most common complication and occurred in 9 of the 13 foals treated surgically.