Page 713 - The Veterinary Care of the Horse

called the soft palate. The upper part is the nasopharynx which is part of the horse’s airway.

The lower part, the oropharynx is continuous with the back of the mouth.
VetBooks.ir button that is done up, and the epiglottis lies on top of the soft palate. The seal is sufficiently
The larynx opens into the nasopharynx through a hole in the soft palate, rather like a

tight that neither air nor food passes between the two parts of the pharyngeal cavity. Gurgling

occurs when this anatomical relationship is disrupted. For a short period of time during
maximal exercise, the soft palate is displaced above the epiglottis. This obstructs the flow of
air and causes turbulence leading to loss of performance and loud inspiratory and expiratory

noise. As soon as the horse swallows, the soft palate and larynx return to their normal
position and the horse can breathe properly again.

Causes

There are numerous factors that may predispose the horse to dorsal displacement of the soft
palate. These include the following.

• Lack of fitness.

• Exhaustion.

• The presence of blood or mucus in the pharynx, e.g. from recurrent airway disease, or
exercise-induced pulmonary haemorrhage.

• Airway obstruction, e.g. if the horse has a degree of laryngeal hemiplegia the reduced
airway diameter causes a high negative pressure in the nasopharynx during inspiration

which may cause the soft palate to be sucked upwards into the airway.

• Inflammation of the pharynx, e.g. pharyngeal lymphoid hyperplasia.
• Ulceration or cysts on the soft palate or epiglottis.

The larynx and tongue are joined by the hyoid apparatus which is important in the process of
chewing and swallowing. Anything that pulls the tongue or larynx backwards may cause
‘unbuttoning’ of the larynx from the soft palate. It is thought that the powerful muscles on the

underside of the neck could sometimes be responsible for pulling the larynx backwards. The
horse’s bit may also be a factor for the following reasons.

• It breaks the airtight seal of the lips and air entering the mouth could elevate the soft
palate.

• If it causes pain it may trigger a gagging reflex.

• When a horse tries to evade the bit, the base of the tongue pushes upwards onto the soft
palate and may elevate it.