Page 711 - The Veterinary Care of the Horse

cases of severe or complete paralysis, the wasted dorsal cricoarytenoid muscle is replaced by

a prosthesis. A band of material is used to tie the left side of the larynx in the open position.
VetBooks.ir This may be combined with a ventriculocordectomy (described above). The operation is
usually successful in relieving the obstruction of the airway and may improve exercise

tolerance but it is not without complications. With the larynx held permanently open, food
material sometimes enters the trachea during swallowing. For a small number of horses this

is a serious problem and the horse is left with a persistent cough. Aspiration pneumonia is a
rare complication. Other complications include:

• post-operative infection

• failure of the prosthesis to open the airway sufficiently
• collapse of the left side of the larynx post-operatively due to the prosthesis cutting

through the cartilage.

Nerve and muscle grafting Techniques have been tried where a branch of the first cervical
nerve and pieces of the omohyoideus neck muscle are transplanted as a nerve-muscle pedicle

into the wasted dorsal cricoarytenoid muscle. If the surgery is successful the function of the
larynx continues to improve for up to a year following the surgery. This operation is not

widely available.
Direct nerve implantation A new technique involving direct implantation of the first or

second cervical nerve into the dorsal cricoarytenoid muscle has recently been described. This
procedure is combined with removal of the left ventricle and vocal cord. The procedure

resulted in re-innervation in 11 out of 12 cases and an improvement of laryngeal function at
exercise in 9 of the 14 horses in the study within 12 months of the surgery.

Electrical stimulation Some improvement in laryngeal function has been reported with

electrical stimulation of the laryngeal muscles and the recurrent laryngeal nerve with
electroacupuncture if treated early in the course of the disease. More work is needed to
develop and assess the efficacy of this procedure.

Prognosis

Following surgery a success rate ranging from 45–70% is reported. If the above techniques

are not successful, a tracheotomy is sometimes performed as a last resort.

Tracheotomy and tracheostomy

A tracheotomy is used as a temporary or emergency treatment if the upper airway is