Kersjes A.W., F.Nemeth и E L.J.Rutgers - Atlas of Large Animal Surgery/Атлас по хирургии крупных животных

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Chapter i T H E H E A D / Nose 1-12

057

i-i 2 Treatment of nasolacrimal orifice atresia

Atresia of the nasal opening of the tear duct may be the cause of chronic

lacrimation in foals. In some cases the distal part of the duct is also absent.

Surgery. Surgery is performed under general anaesthesia. A catheter is in-

troduced into the lacrimal papilla of either the upper or lower eyelid [057].

The catheter is then advanced carefully down the tear duct, until the tip is

palpable beneath the nasal mucous membrane [058]. The nasal mucosa and

the mucosa of the blind end of the duct are incised over the tip of the ca-

theter [059], after which the catheter is pushed through the opening cre-

ated [060]. If accessible, the mucous membrane of the duct is sutured to

the nasal mucous membrane with simple interrupted sutures of fine ab-

sorbable material. The catheter is then sutured to the skin in the nasal and

eyelid regions, and left in place for at least two weeks. If suturing of the

mucosal layers is impossible the catheter must be left in place for a longer

period (3-4 weeks), after which time the wound edges have healed and the

opening remains patent.

Postoperatively antibiotic ophthalmic ointments are administered into the

conjunctival sac, and corticosteroids may be added for several days to re-

duce oedema and fibrosis around the created orifice.

Chapter 2 The neck

Chapter 2 THE NECK / Muscles 2-1

062

2-1 Myectomy (Forssell) and accessory nerve neurectomy

In crib-biting the horse grips a fixed object (e.g. manger) with the

(upper)incisor teeth, arches the neck and attempts to swallow air; horses

which succeed in swallowing air are called windsuckers. Some horses are

'free' windsuckers, these display the vice without cribbing. Initially non-

surgical methods (cribbing strap, aversion therapy) may be used, but are

often unsuccessful, and the owner requests surgical treatment. This con-

sists of partial resection of the paired ventral neck muscles: sternohyoideus,

omohyoideus, sternothyroideus and sternocephalicus. Instead of myect-

omy of the latter, neurectomy of the ventral branch of the accessory nerve

may be performed.

Surgery. The horse is positioned in dorsal recumbency under general

anaesthesia. Excessive extension of the neck should be avoided because of

possible stretching of the recurrent nerve, the head should thus be resting

at an angle of about 30°.

A midline skin incision of 30-40 cm is made from the hyoid bone caudally.

The whole operation may be accompanied by considerable haemorrhage,

and careful haemostasis is obligatory. The skin and subcutis are dissected

and reflected laterally [061]. The omohyoideus muscle is carefully separ-

ated from the jugular vein. The omohyoideus and sternohyoideus are

transected near their insertions [062] and reflected back to the caudal edge

of the wound, whereafter the entire muscle section is removed [063]. This

exposes the cranial part of sternothyroideus [064] which is easily dissected

from the trachea and excised [065]. Next the sternocephalicus is freed by

blunt dissection after incising its sheath longitudinally. The muscle is tran-

sected at the caudal edge of the incision [066], reflected cranially and se-

vered through its tendon [067].

Instead of sternocephalicus myectomy, denervation of the muscle may be

performed. The purpose of neurectomy of the ventral branch of the ac-

cessory nerve is to diminish the post-operative deformity of the region.

The nerve is located on the dorso-medial aspect and runs parallel with the

Chapter 2 THENECK/ Muscles 2-1

066

muscle. The neurectomy site is proximal to the entry of the nerve into the

muscle; at least 3 cm are removed [068]. The procedure may be carried out

before or after myectomy of the other muscles. The skin is closed with in-

terrupted mattress sutures. At both ends of the wound a drain is placed.

Proper functioning of the drains must be checked twice daily, and they

must not be removed before 3 days.

Postoperatively the horse is confined for about three weeks, and care is

taken that the stall contains no objects that may be grasped with the

incisors or on which the wound may be rubbed.

Chapter

2 THE

NECK

Larynx

and

trachea

2-2

070

2-2 Laryngotomy - cricoarytenoidopexy and ventriculectomy

Inspiratory dyspnoea due to laryngeal hemiplegia (roaring) is a common

clinical sign in horses requiring surgical treatment to enlarge the reduced

laryngeal lumen [o6gA]. Many procedures to alleviate laryngeal hemiplegia

have been utilized. Of the various techniques the combination of cricoary-

tenoidopexy with unilateral or bilateral ventriculectomy has given the best

results. Instead of lycra, a double ligature of heavy-sized chromic catgut is

preferred for the cricoarytenoidopexy.

Surgery. The horse is positioned in right lateral recumbency in general

anaesthesia with the head and neck extended.

A 10 cm skin incision is made parallel and ventral to the linguofacial vein

from the cranial border of the larynx to the second tracheal ring [070]. Sub-

cutaneous fascia is incised with a scalpel. The dorsolateral aspect of the

larynx is approached by blunt dissection. The muscular process of the

arytenoid cartilage is penetrated from medial to lateral with a pointed

Deschamp's needle [071]. The double chromic catgut is threaded through

the eye of the needle and pulled through the muscular process. The medial

part of the ligature is brought under the crycoarytenoid muscle using the

Deschamp's needle. The needle is then passed, from medial to lateral,

through the caudal border of the cricoid cartilage, about 2 cm lateral to the

median ridge. The needle passes through the cartilage, but not through

mucous membrane into the laryngeal lumen. The needle emerges approxi-

mately i cm cranial to the caudal border of the cricoid [072]. The medial

part of the thread is threaded into the needle and pulled through the cricoid

cartilage [073]. The two ends of the ligature are tied [074] with sufficient

tension to fully retract the arytenoid cartilage; this can be checked by lar-

yngoscopy [0693].

A vacuum drain is placed in the wound cavity. The subcutaneous and deep

fascial tissues are closed with a simple continuous suture and the skin with

interrupted sutures, using synthetic absorbable material.

The patient is then positioned in dorsal recumbency; the nose is supported

Chapter

2 THE

NECK

Larynx

and

trachea

2-2

074

to prevent extreme extension of the neck. The laryngeal cavity is opened

(see 2-3); the crycoid cartilage is not incised.

The mucous membrane of the left laryngeal saccule is removed. The rim of

the laryngeal saccule is incised on its caudal border [075] and the index

finger is brought submucosally to free and then evert the mucous mem-

brane. The everted mucous membrane is resected with scissors as close to

the base as possible without damaging the adjacent cartilage [076]. To

prevent foreign body aspiration during recovery and recuperation the skin

is closed with a few non-absorbable interrupted sutures. If postoperative

dyspnoea occurs a tracheotomy tube is inserted through the laryngotomy

wound, or tracheotomy (see 2-5) is performed.

Antibiotics are administered. The vacuum drain is removed after two to

three days. The laryngotomy wound is cleansed daily and heals satisfac-

torily by second intention. The horse is confined to a box for 4 weeks. After

two months at pasture the horse may be returned to training.

Chapter

2 THE

NECK

Larynx

and

trachea

2-3

°77

2-3 Laryngotomy - extirpation of subepiglottal cyst

Inspiratory and/or expiratory noise at work and dyspnoea due to epiglottal

lesions (subepiglottal cyst, abscess, and epiglottic entrapment) are oc-

casionally observed in horses. To enable surgery in the area of the soft pa-

late and epiglottis, a laryngotomy must be performed. The surgical tech-

nique for removal of a subepiglottal cyst is described here. Diagnosis is

made by endoscopic examination [077].

Surgery. The patient is positioned in dorsal recumbency under general

anaesthesia. A 10 cm midline incision is made over the larynx through the

skin and through the midline junction of the sternohyoid muscles. The

crycothyroid membrane is incised in the midline. In this condition, in-

cision through ventral midline of the crycoid cartilage is necessary to gain

space. A self-retaining wound retractor exposes the laryngeal cavity [078].

After the endotracheal tube has been removed exposure of the subepigottal

cyst is possible. The apex of the epiglottis is drawn caudad from the naso-

pharynx into the laryngeal lumen, thereby presenting the cyst on the

ventral surface of the epiglottis in the surgical field. Traction on the epi-

glottis is accomplished by grasping the aryepiglottic fold, on the lateral wall

of the pharynx between the base of the epiglottis and the arytenoid, with a

sponge forceps. A Lakey traction forceps applied to the apex of the epiglot-

tis retains it in position.

The mucosa surrounding the cyst is carefully grasped with Allis tissue for-

ceps [079], incised and the cyst is then dissected bluntly from the sur-

rounding tissue [080]. Excess mucosa may be excised. The wound is left

open. Only the skin is closed with a few non-absorbable interrupted

sutures. The laryngotomy wound heals by second intention. The patient is

box rested for 4 weeks.

Chapter

2 THE

NECK

Larynx

and

trachea

2-4

2-4 Laryngotomy - in bovine necrotic laryngitis

Necrotic laryngitis associated with calf diphtheria is the most important

cause of laryngeal dyspnoea in young cattle. The results of medical treat-

ment are often disappointing. The aim of surgical treatment is to excise

necrotic cartilage and/or granuloma and produce a permanent widening of

the glottis.

Surgery. Prior to laryngotomy, a tracheotomy is performed (see 2-5). The

patient is placed in dorsal recumbency under general anaesthesia, or under

sedation in combination with local infiltration analgesia. If laryngeal intub-

ation is impossible an endotracheal tube must be inserted via the trach-

eotomy wound. The inflated cuff prevents the passage of blood into the

lungs during surgery.

The skin and subcutanuous tissue are incised in the midline and the ster-

nohyoid muscles are separated. A midline incision is made through the

crycothyroid ligament, thyroid cartilage and the first 2 tracheal cartilages

[081]. (The thyroid cartilage is cut with a strong pair of scissors). Topical

analgesia of laryngeal mucosa is necessary if general anaesthesia has not

been used. The laryngeal cavity is exposed by means of Volkmann retrac-

tors. In most cases the.necrotic lesions and granulomas are clearly visible.

The depth of (a) possible fistulous tract(s) is determined with a probe

[082]. Necrotic debris, including cartilage sequestra, are removed by curet-

tage [083]. After cleaning the laryngeal cavity, the skin is closed with non-

absorbable material in an interrupted pattern [084].

Systemic antibiotics are administered. The tracheotomy tube is removed as

laryngeal swelling reduces and has less effect on respiration.

Chapter

2 THE

NECK

Larynx

and

trachea

2-5

2-5 Tracheotomy

Tracheotomy is usually an emergency procedure and is indicated to re-

lieve dyspnoea caused by acute nasal, laryngeal or proximal tracheal ob-

structions. Tracheotomy is also indicated prior to some operations on the

nose, paranasal sinuses or larynx.

Surgery. Tracheotomy is usually performed on the standing animal under

local infiltration analgesia, but may also be carried out on the recumbent

patient. The head and neck of the animal are extended and an approxim-

ately 7 cm ventral midline skin incision is made in the cranial third of the

neck at the level of the 4th-6th tracheal ring. After incising the thin cut-

aneous muscle in the midline, the longitudinal junction of the sternohyoid

muscles is divided and the trachea exposed. The muscles and skin are

spread with a wound retractor.

If temporary tracheotomy is indicated, a tracheal annular ligament is pierc-

ed with a scalpel and a tracheal tube (ovoid in cross-section) is inserted.

If the tracheotomy tube is to remain for a longer period, partial resection of

a tracheal ring is performed, (i) A tracheal window is produced by partial

resection of one tracheal ring [085]. The disc to be removed is grasped with

forceps. (2) To prevent the tracheal ring from collapsing, resection of a

semi-disc of the tracheal rings proximal and distal to an incision through

the annular ligament is recommended [086,087].

After tracheotomy a self-retaining tube is inserted [088] and the skin edges

are sutured around the tube in a simple interrupted pattern. Since there is

considerable mucous secretion for the first few postoperative days, the tube

must be cleaned frequently. Later on, when the discharge has reduced, air

passage through the tube is checked daily, but the intervals of cleaning may

be prolonged. After the tube is withdrawn, the tracheotomy wound heals

by second intention.

Chapter j The thorax