Over the months we had her we noticed that she had a number of behavioral issues:
- head shy on one side
- tense and anxious about giving to the bit
- difficulty bending
- not reacting as expected to the bit
- very slow eating
During her last dental appointment we found out why! Both sides of her mouth were ulcerated and she had terrible hooks on both sides of her mouth.
Rostral hooks are the overgrowth of the front premolars (1/6 or 2/6 tooth). The hooks are caused by discrepancies in the length and position of the upper jaw (maxilla) and the lower jaw (mandible). When they do not match perfectly, hooks develop. Often, if there is a rostral hook (up in the front, there is a caudal hook (or ramp) that develops in the back of the mouth as well.
Sometimes it isn't the horses conformation, but simply the height at which the horse is fed that causes the mandible and maxilla to be misaligned. If the horse eats off of the ground, then all of the teeth are in the natural position. When a horse is fed up higher, as seen in a lot of show barns using hay feeders, the mandible shifts back, causing the teeth to grid out of occlusion and cause the rostral hooks and caudal hooks.
When horses have hooks, the teeth can no longer grind against one another forward and back, causing the horses to have to chew up and down instead of in their natural griding pattern. It also presents a very large problem for horses needing to release their jaw to the bit, forcing their mouths open with bit pressure instead of allowing them to relax into the pressure of the bit.