The TSD should be used only after your veterinarian has diagnosed an upper airway problem such as dorsal displacement of the soft palate that is likely to be improved by positioning the larynx (voicebox) in a more forward and upward position which has been shown to be beneficial in stabilizing the upper airway during strenuous competition. 

It is comprised of a head strap with lifting mechanism and Figure-8 noseband. The lifting mechanism, must be placed just behind the depression formed by the basihyoid bone (consult your veterinarian). The lifting mechanism is then secured forward with the Figure-8 nose band. 

For harness race horses (trotters or pacers), place the TSD-I first, then the head halter or caveson, then the bridle. 

For Thoroughbred race horses, you can use either the TSD-I under your normal bridle or the TSD-II model (includes bridle cheeks and crown). 

With either TSD model, the front loop (with buckle) of the Figure-8 is ultimately positioned and tightened in front of the bit. 

A tongue-tie may be applied as well but is not usually needed.

Step 1. Place the crown piece over the poll and place the head strap of the TSD so that it rests immediately in front of the ears (Figure 1).

Step 2. Place the tip of the lifting mechanism just behind the depression (A) formed by the basihyoid bone on the midline between the jaws (Figure 2). You can identify this depression by placing a finger at the “*” and moving backwards. Place the lifting mechanism immediately behind the first bone felt. 

Tighten the head strap buckle so that the tip of the lifting mechanism fits comfortably in this depression (A). Do not over tighten. (You should be able to place several fingers under the head strap at the throat.)

Step 3. Securely tighten the Figure-8 nose band by pulling on straps passing over the nose so that, with the head extended, the tip of the lifting mechanism remains in position behind the basihyoid bone. If necessary, adjust the tightness of the head strap. Do not buckle Figure-8 yet

Step 4. Place the bridle and securely buckle the Figure-8 with the strap passing in front of the bit.

Precautionary statement: As for any device (bridle, halter, cribbing strap) with straps crossing over the throat area one must exercise care to not excessively tighten straps such that there is compression of the trachea (windpipe) or nasopharynx. Customary precautions for placement of a Figure-8 noseband must be used---do not place this device over the nostrils so that there is obstruction of nasal airflow.