Quarter Horse with a "nose" problem.
Baxter is a 5 year old quarter gelding shown in western pleasure. Prior to my examining Baxter he had been floated once, when he was two. Before this current show season he was normal while showing.
This season, however, Bob noticed that Baxter "nosed up" four or five times during each class. Regardless of the type of bit or bridle, Baxter would raise his head and stick his nose out and up. Baxter was shown by Bob's daughter, Angela. Angela was an experienced, although young rider, and showed Baxter on a loose rein.
Examination
No external abnormalities were found.
Opening the lips revealed a clue to Baxter's problems. The upper four central incisors had a lip of excess tooth on the front edge. This told me that the mandible or jaw was not moving forward, or downward when Baxter lowered his head and the nose was pointed toward the ground.
When the mandible or jaw and lower incisors fail to move forward and get even with the front of the upper incisors when the horse grazes, the front edge of the upper incisors is not worn off. Eventually a lip of unworn tooth appears.
The extra lip was not the primary problem, but secondary to a molar malocclusion. After insertion of a full mouth speculum, the cause of Baxter's performance problem was obvious.
Baxter had two major molar malocclusions. Two large front hooks and exaggerated transverse ridges on all the molar chewing surfaces. These two problems stopped normal forward jaw motion, leading to constant tension in the masseter muscle and temporomandibular joint (TMJ) pain.
Baxter also had lacerations to the cheek just behind the corner of the mouth and lacerations to the cheek where the upper last molar touched the cheek.
Correction
The first procedure was a performance float that shaped both upper and lower arcades to prevent soft tissue damage.
Using a rotary cable grinder I removed the upper front hooks and the excess transverse ridges. The chewing surface should not be smooth when finished, but left with an irregular, rough surface.
I then checked the chewing surfaces to be sure they were parallel and there would be uniform contact, end to end when Baxter chewed.
After all corrections, I lowered Baxter's nose and the jaw immediately moved forward allowing the upper and lower incisors to be even. In this position I checked to see if the first cheek teeth (second premolars) were positioned normally to each other. They were not. Baxter had an upper premolar overjet.
This means a little extra shaping on the upper teeth, with each floating, to stop reoccurrence of the hooks.
Resolution
Baxter stopped nosing up the very next time he was ridden. Also, even though Baxter did not show any obvious chewing problems, he started eating faster. Since the jaw could now move freely side to side and front to back, the inflammation in the TMJ resolved.