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Equine Health Resource

Dorsal Displacement of Soft Palate, DDSP

Synonyms: Choking Down

Normal horses can only breathe through their nose. The opening of the windpipe (the larynx) fits within a tube formed by the folds of the nasopharynx, the common opening of the two nasal passages, with the floor being the soft palate.

Usually, the epiglottis tip rests on top of the soft palate except during swallowing, and maintains this path of air flow. If the larynx is pulled rearward for any reason, then the soft palate becomes free and the horse mouth breathes for a moment. This dislocation causes a major impediment to air flow in exercising horses, and a choking, fluttering or gurgling sound is made and the performance is interrupted or pace is slowed.

There is some thought that this may be induced by stress as it tends to be seen in maximally exercising horses, such as racehorses. It may also happen when horses at speed open their mouths. In the so called Intermittent cases (IDDSP), the displacement just lasts for seconds. The horse slows down and swallows and that restores normal placement. But the slowdown results in the loss of the race.

When there is a major anatomic problem in the area, it can be a constant problem, and a much easier diagnosis.

There are a variety of treatment options, none of which work all the time. Surgical treatments include teflon augmentation of the epiglottis, laser or conventional surgery on the rear border of the soft palate, and even cutting of the sternothyroideus muscle in the neck, to allow the epiglottis to move forward. The tie forward surgical procedure claims a higher success rate of approximately 80%.

QUESTIONS TO ASK MY VET

  • Are there underlying conditions which might be causing this?
  • What are the treatment options and prognosis for each?
  • PREVENTION

    Treat underlying disorders such as laryngeal hemiplegia, RAO, etc. Maintain excellent levels of fitness. Some use a dropped noseband to keep the horse's mouth closed or a tongue strap to prevent rearward movement of the tongue. These may or may not be effective. Specific bits are claimed to make a difference too but again, there is little evidence for their effectiveness.

    Helpful Outside ResourcesCredible Equine Health Information on the Internet

    Author: Doug Thal DVM Dipl. ABVP

    RELATED REFERENCES

    Dorsal Displacement of the Soft Palate: Winning With Air, Cable C.S. on TheHorse.com website. Available at: http://www.thehorse.com/articles/14186/dorsal-displacement-of-the-soft-palate-winning-with-air. Accessed 2013.

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