• It is speculated that contraction of the sternothyrohyoid (STH) and omohyoid (OH) muscles during forced inspiration may result in caudal retraction of the larynx and predispose the horse to dorsal displacement of the soft palate (DDSP) Soft palate: dorsal displacement.
• Myectomy of the STH +/- OH muscles has been used for the treatment of DDSP with or without the use of other medical or surgical treatments.

Uses

• Dorsal displacement of soft palate Soft palate: dorsal displacement.

Advantages

• Can be performed in the standing horse (STH resection only) → decreased cost and risks with general anesthesia.
• Success rate similar to other surgical treatments such as partial soft palate resection but without serious complications.
• Assessment of results of this surgery are available early in the post-operative period.

Disadvantages

• Limited success where epiglottic hypoplasia is present.
• Post-operative wound healing can be a problem.
• Disfigurement of neck outline.

Alternative techniques

• Same as DDSP Soft palate: dorsal displacement.

Time required

Preparation

• Aseptic skin preparation: 10 min.
• Standing procedure: sedation and local anesthetic infiltration: 10-15 min.
• General anesthesia (GA): induction and maintenance: 20 min.

Procedure

• STH resection under sedation: 20-30 min.
• STH + OH myectomy under GA: 30-40 min.

Decision taking

Criteria for choosing test

• Same as DDSP Soft palate: dorsal displacement.