The head and neck - Volume 2

PRESENTATION

Small animal surgery

BROCHURE

Small animal surgery José Rodríguez (Editor)

Salivary glands

The head and neck

Lips and gingiva Palate and tongue Teeth Larynx Eyeball and adnexa Brachycephalic obstructive airway syndrome

Surgical atlas, a step-by-step guide

The head and neck Volume II

Small animal surgery

SMALL ANIMAL SURGERY

Small animal surgery José Rodríguez (Editor)

Salivary glands

The head and neck

The head and neck Volume II eBook

available

Lips and gingiva Palate and tongue Teeth Larynx Eyeball and adnexa Brachycephalic obstructive airway syndrome

Surgical atlas, a step-by-step guide

The head and neck Volume II

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RETAIL PRICE

The head and neck. Volume 2 expands the presentation of the medical conditions that may affect these body areas and the routine surgical procedures used to manage them. The detailed descriptions of the different surgical techniques are accompanied by a wealth of visual content that will contribute to a better understanding of these techniques.

TARGET AUDIENCE:

✱ Small animalvets.

Surgery ✱ Veterinary students FORMAT: 23×29.7 cm

€90

NUMBER OF PAGES: 288 NUMBER OF IMAGES: 800 BINDING: hardcover

Authors JOSÉ RODRÍGUEZ, LDO. VET., PHD PhD in veterinary medicine (Complutense University of Madrid, Spain). Professor in the area of animal medicine and surgery at the Department of Animal Pathology of the University of Zaragoza (Spain).

Diploma in Ocular Pathology and Surgery by the Autonomous University of Barcelona.

KEY FEATURES: ➜ Procedures explained step-by-step in images, and complemented by diagrams. ➜ High quality of technical and graphic content. ➜ Videos for visualisation of the different phases of each intervention and of patients’ clinical signs. ➜ Recommendations and tips and tricks of great practical utility.

Presentation of the book “Success in life is not always to win, but never to lose heart.”

Napoleon Bonaparte (1769-1821) In 2003, a fascinating project emerged: to capture in images how the authors plan and perform their surgeries, in order to help other surgeons with the planning and execution of their interventions.

“Surgery atlas, a step-by-step guide” started with the volume The pelvic area followed by The caudal abdomen, The cranial abdomen and The thorax. Now comes the turn for The head and neck. The diseases and injuries found in this area are not only very common in everyday practice but can also have important functional and aesthetic repercussions.

Their successful resolution requires correct planning and surgical execution.

There are many procedures performed in the head and neck region. As the coordinator, I therefore decided to divide them between two volumes, as I have done previously with the abdomen.

This second volume of Head and neck focuses on the salivary glands, teeth, larynx and ocular surface. It includes a separate section on brachycephalic obstructive airway syndrome.

The main objective of this book is to serve as an additional reference for the veterinary surgeon who performs these operations more or less frequently, and as a guide for novice surgeons taking their first steps in surgical interventions that require precision and delicacy for optimal results.

As in the previous volumes, the step-by-step images of the interventions are complemented by diagrams and illustrations to better understand the anatomy of the area and the surgical approach, and by high-quality videos for visualisation of the different phases of each intervention.

As the author and coordinator of this book I hope that the following pages will offer you the information, recommendations, tips and tricks to help make your surgical interventions safer and the recovery of your patients speedier.

José Rodríguez Gómez

The head and neck. Volume II

The author José Rodríguez Veterinary degree and PhD from the Complutense University of Madrid, Spain (1982 and 1985).

Full professor in the Department of Animal Pathology at the University of Zaragoza, Spain.

Degree in ophthalmological pathology and surgery at the Autonomous University of Barcelona, Spain.

Author and coordinator of the series “Surgical atlas, a step-by-step guide”, which includes the books: The pelvic area, The caudal abdomen, The cranial abdomen, The thorax, Bloodless surgery, Basic principles and techniques, The gastrointestinal tract. Clinical cases, Surgical techniques, Errors and complications in surgery and Head and neck (vol. I), which have been translated into several languages including English, French, German, Italian, Japanese, Chinese and Korean.

Collaborators Jorge Llinás Veterinary degree from the University of Zaragoza, Spain.

Diploma of advanced studies from the University of Zaragoza.

University specialist in maxillofacial surgery.

Director and surgeon of the Valencia Sur veterinary hospital (Valencia, Spain).

President of the Spanish Society of Veterinary Laser and Electrosurgery.

Co-author of the books Bloodless surgery, Basic principles and techniques and Head and neck I of the collection “Surgical atlas, a step-by-step guide”.

Roberto Bussadori Veterinary degree from the University of Milan, Italy.

European veterinary PhD. Soft tissue surgeon (thorax, cardiovascular and respiratory systems) of the Gran Sasso veterinary clinic of Milan, Italy.

Master’s degree in microsurgery, experimental surgery and transplantation.

Surgeon at the Valencia Sur veterinary hospital (Valencia).

Co-author of the books Basic principles and techniques and Head and neck I of the collection “Surgical atlas, a step-by-step guide”.

Cristina Bonastre Veterinary degree from the University of Zaragoza, Spain.

PhD from the University of Caceres, Spain.

Assistant professor at the Department of Veterinary Pathology, University of Zaragoza.

Amaya de Torre Veterinary degree from the University of Zaragoza, Spain.

Intern in small animal medicine and surgery at the Veterinary Hospital of the University of Zaragoza.

Director of the Hispanidad veterinary clinic (Zaragoza).

Associate professor at the Department of Animal Pathology, University of Zaragoza.

Luis García Veterinary degree from the University of Zaragoza, Spain.

Director of the Ejea veterinary clinic (Zaragoza).

Vice-president of the Spanish Society of Veterinary Laser and Electrosurgery.

Alicia Laborda Veterinary degree and PhD from the University of Zaragoza, Spain.

Intern in small animal medicine and surgery at the Veterinary Teaching Hospital of the University of Zaragoza.

Tenured professor at the Department of Animal Pathology, University of Zaragoza.

Carolina Serrano Veterinary degree and PhD from the University of Zaragoza, Spain.

Intern in small animal medicine and surgery at the Veterinary Teaching Hospital of the University of Zaragoza.

Veterinarian of the Research Group in Minimally Invasive Techniques at the University of Zaragoza.

Tenured professor at the Department of Animal Pathology, University of Zaragoza.

Manuel Alamán Veterinary degree from the University of Zaragoza, Spain.

Intern in small animal medicine and surgery at the Veterinary Teaching Hospital of the University of Zaragoza.

Veterinarian at the Valencia Sur veterinary hospital (Valencia, Spain).

Associate professor at the Department of Animal Pathology, University of Zaragoza.

Juan Ramón Arrazola Veterinary degree from the University of Zaragoza, Spain.

Degree in biology from the Complutense University of Madrid, Spain.

Veterinarian at the Valencia Sur veterinary hospital (Valencia, Spain).

Maria Teresa Mangas Veterinary degree from the University of Extremadura, Spain.

Anaesthetist at the Jesús Usón Research Centre (Caceres).

Head of anaesthesia at the Valencia Sur veterinary hospital (Valencia, Spain).

The head and neck. Volume II

Ángel Ortillés Veterinary degree and PhD from the University of Zaragoza, Spain.

Master’s degree in Small animal medicine and surgery from the University of Zaragoza.

Academic teaching scholarship at the University of Zaragoza.

Resident in ophthalmology at the Veterinary Teaching Hospital of the Autonomous University of Barcelona.

Javier Mazón Veterinary degree and PhD from the University of Zaragoza, Spain.

Associate Professor at the Faculty of Veterinary Medicine of the Catholic University of Valencia, Spain.

Daniel Herrera Diploma in veterinary ophthalmology from the Autonomous University of Barcelona, Spain.

Diplomate of the Latin-American College of Veterinary Ophthalmologists (CLOVE).

Associate Professor at the Faculty of Veterinary Sciences of the University of Buenos Aires, Argentina.

Ana Whyte Veterinary degree and PhD from the University of Zaragoza, Spain.

Full professor at the Department of Animal Pathology.

Specialist in veterinary dentistry and maxillofacial surgery from the Complutense University of Madrid, Spain.

Fidel San Román Ascaso Veterinary degree and PhD. Professor of surgery, Complutense University of Madrid, Spain.

Diplomate of the European College of Veterinary Dentistry.

Degree in dentistry and Degree in medicine and surgery.

Jesús María Fernández Veterinary degree and PhD. Specialist in veterinary dentistry and maxillofacial surgery from the Complutense University of Madrid, Spain.

Associate Professor at the Department of Medicine and Surgery, Complutense University of Madrid.

Rio Duero veterinary clinic (Madrid).

Juan Ignacio Trobo Veterinary degree and PhD. Tenured professor at the Complutense University of Madrid, Spain.

Specialist in veterinary dentistry and maxillofacial surgery from the Complutense University of Madrid.

Degree in dentistry. Master’s degree in implant prosthetics.

Fidel San Román Llorens Veterinary degree and PhD. Associate Professor of Surgical Pathology and Surgery of the University of Zaragoza, Spain.

Specialist degree in traumatology and orthopaedics in pets from the Complutense University of Madrid.

In charge of traumatology and vertebral surgery at the Veterinary Clinical Centre of Zaragoza.

Table of contents 1. Introduction

Laryngeal collapse Laryngeal polyps Laryngeal tumours

2. Salivary glands Overview Sialocele Salivary stones Tumours

7. Eyeball and adnexa Overview Basic principles Anaesthetic considerations The eyelids

3. Lips and gingiva Lips

Overview Entropion Tumours

Overview Lip fold pyoderma Excessive drooling Wounds Tumours Cleft lip

The eyelashes Congenital disorders

Third eyelid

Gingiva Overview Inflammatory lesions and tumours

4. Palate and tongue Palate Overview Small palatine defects Large palatine defects

Tongue Necrotic glossitis Tumours

5. Teeth Dental and oral diseases. Overview Dental extractions

6. Larynx Overview Laryngeal paralysis

Editorial Servet

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Overview Depigmentation Luxation and eversion Protrusion of the lacrimal gland Tumours

The conjunctiva Overview Conjunctival lesions

The cornea Overview Complicated lesions and descemetoceles Specific corneal lesions Dermoids

8. Brachycephalic obstructive airway syndrome Overview Stenotic nares Soft palate resection Complications. Postoperative care

Plaza Antonio Beltrán Martínez, 1 Centro Empresarial El Trovador planta 8, oficina 50002 Zaragoza, Spain

■

+34 976 461 480

Small animal surgery JosĂŠ RodrĂ­guez (Editor)

Salivary glands Lips and gingiva Palate and tongue Teeth Larynx Eyeball and adnexa Brachycephalic obstructive airway syndrome

Surgical atlas, a step-by-step guide

The head and neck Volume II

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The head and neck II

Overview The larynx is made up of the epiglottis, thyroid, cricoid, arytenoid, and interaritenoid sesamoid cartilages (Fig. 1).

The arytenoid cartilages are formed by the cuneiform processes, which are the most rostral of the processes and join ventrally in the aryepiglottic fold. The corniculate processes form the dorsal part of the entry into the larynx and are located behind the cuneiform processes. They are joined dorsally by the interarytenoid sesamoid cartilages. The dorsal cricoarytenoideus muscle inserts on the muscular process on the dorsolateral side and is responsible for the abduction of the arytenoid cartilages and the cricoarytenoid joint.

José Rodríguez, Jorge Llinás, Luis García, Roberto Bussadori, Carolina Serrano Laryngeal disease causes respiratory difficulty that can be distressing for the patient, of great concern for its owner and an important diagnostic and therapeutic challenge for the veterinarian in charge.

If a dyspnoeic animal is presented, the initial treatment is oxygen therapy, but it should be applied without causing greater stress, since these patients can collapse and suffer syncope if restrained (Fig. 2).

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Fig. 1. Radiograph of the larynx showing the following

structures: hyoid apparatus (white arrow), soft palate (black arrow), epiglottis (yellow arrow), arytenoid (blue arrow), thyroid (green arrow) and cricoid cartilages (orange arrow).

Fig. 2. In a dyspnoeic patient, oxygen should be

administered as long as it does not involve additional stress increasing the patient’s anxiety. This dog suffered a stage III laryngeal collapse.

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Larynx / Overview

Corniculate process Laryngeal entrance Cuneiform process Vocal cord Aryepiglottic fold

Vestibular fold

Epiglottis

Cuneiform process Corniculate process Thyropharyngeus m.

Cricopharyngeus m.

Epiglottis

Oesophagus

Thyrohyoideus m.

Trachea Sternohyoideus m.

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Thyroid cartilage

Sternothyroideus m.

Arytenoid cartilage

Cuneiform process of the arytenoid cartilage

Cricoid cartilage

Ventricularis m.

Corniculate process of the arytenoid cartilage Transverse arytenoid m.

Dorsal cricoarytenoid m.

Articulation with thyroid cartilage

Epiglottis

Cricoid cartilage Laryngeal ventricle Lateral cricoarytenoid m.

Thyroarytenoid m.

Cricothyroid m.

Thyroid cartilage (displaced)

Vocalis m.

Cricothyroid ligament

Fig. 3. Anatomical

structures of the larynx.

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The head and neck II After the initial stabilisation of the patient, a complete physical examination should be carried out, which consists of observing mentation, the posture of the neck and the head, as well as the type of breathing. It is very important to perform a proper auscultation of the chest, neck and larynx.

In animals with anterior airway obstruction, inspiration requires an obvious effort and is accompanied by stridor.

See video Laryngeal stridor

Laryngeal paralysis and laryngeal collapse are the most common causes of anterior airway obstruction.

Anterior airway obstruction can cause non-cardiogenic pulmonary oedema or aspiration pneumonia, conditions that complicate and aggravate the respiratory problem.

In some patients the administration of sedatives is indicated to reduce anxiety and the negative inspiratory pressure that closes the larynx further. Acepromazine (0.001-0.05 mg/kg IV or IM) or butorphanol (0.1-0.2 mg/kg IV or IM) can be used.

The differential diagnosis is based on the physical examination, on craniocervical radiography and, above all, on the direct inspection of the larynx under sedation or superficial anaesthesia to avoid depressing laryngeal movement. In a patient without laryngeal paralysis, normal movement of the arytenoid cartilage can be observed during breathing.

Clinical signs in patients with anterior airway obstruction can include: ■

Inspiratory and/or expiratory stridor or stertor

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Cyanosis

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Extension of the head and neck

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Exercise intolerance

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Collapse

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Loss of consciousness

See video Laryngoscopy in a healthy patient

Possible causes of obstruction of the anterior airways can include: 126

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Inflammation or oedema of the larynx or pharynx

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Laryngospasm

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Foreign bodies

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Laryngeal or tonsillar tumours (Fig. 4)

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Elongation of the soft palate (Fig. 5)

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Laryngeal collapse (Fig. 6)

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Laryngeal paralysis

Fig. 4. This dog suffered a carcinoma of the left tonsil

that blocked the larynx.

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Larynx / Overview

Fig. 5. In brachycephalic dogs, the soft palate is

elongated and increased in thickness, obstructing the larynx to a greater or lesser extent.

a

127

b

Fig. 6. Laryngeal collapse is caused by a degeneration

of the arytenoid cartilages which are unable to keep the larynx open during inspiration. The corniculate processes (yellow arrows) and the cuneiform processes (blue arrows), which are displaced medially, and the eversion of the laryngeal ventricles (orange arrows) occlude the entry of air into the trachea.

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The head and neck II

Laryngeal paralysis In laryngeal paralysis, the arytenoid cartilages and vocal cords cannot open during inspiration. The glottis (rima glottidis) does not open, increasing the resistance and speed of the passage of air through the larynx. This phenomenon, together with the associated increased respiratory rate, causes inflammation and oedema of the mucosa of the arytenoid cartilages, further aggravating the obstruction, thus generating a vicious circle. Suction and medial displacement of said cartilages and vocal cords will aggravate the laryngeal obstruction.

Manuel Alamán, José Rodríguez, Luis García, Jorge Llinás, Roberto Bussadori, Carolina Serrano

In cases of moderate unilateral laryngeal paralysis, patients may be asymptomatic, only manifesting clinical signs in situations of stress and physical exercise.

Laryngeal paralysis accounts for 40 % of laryngeal disease in the dog, but is rare in cats. Among the main causes are trauma, tumours and iatrogenic injury.

See video Laryngeal paralysis

Paralysis of arytenoid cartilages and vocal cords can be unilateral (usually on the left side) or bilateral. The process is progressive and mainly affects large or giant breed dogs older than 9 years, but it is also diagnosed in medium and small breeds suffering from other respiratory conditions.

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Laryngeal paralysis is usually acquired, generally secondary to recurrent laryngeal nerve injury or dysfunction of the intrinsic laryngeal muscles, but it can also be congenital. The most common causes include trauma, cervical masses and neuromuscular disease, the most prevalent one being geriatric onset laryngeal paralysis polyneuropathy (GOLPP), formerly known as idiopathic laryngeal paralysis. The Labrador Retriever, Golden Retriever, St. Bernard and Irish Setter are the breeds most predisposed to suffer from acquired laryngeal paralysis (Table I). The congenital form most commonly occurs in breeds such as the Bouvier des Flandres, Bull Terrier, Siberian Husky, Alaskan Malamute, Dalmatian and Pyrenean Mountain Dog. In cases of congenital laryngeal paralysis, clinical signs usually appear before the first year.

See video Congenital laryngeal paralysis

Patients with laryngeal paralysis can aspirate saliva or food and develop secondary pneumonia.

Among the most frequent clinical signs in cats are tachypnoea and dyspnoea, although they can also present with dysphonia, inspiratory stridor, lethargy and anorexia.

Table I. Causes of secondary laryngeal paralysis Aetiology Accidental cervical trauma

■ Strangulation ■ Hemilaminectomy (ventral slot decompression) ■ Thyroidectomy / parathyroidectomy ■ Abscesses, granulomas

Cervical and thoracic masses

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■ Road traffic accident

■ Cranial thoracic surgery

Secondary laryngeal paralysis occurs mostly in adult and geriatric males of large breeds.

Dogs with polyneuropathic laryngeal paralysis can present with muscular atrophy and weakness of the hind quarters and, in 75 % of cases, with oesophageal abnormalities (oesophageal dysfunction, megaoesophagus) that increase the risk of aspiration pneumonia.

■ Penetrating cervical lesions

■ Tracheal surgery

Surgical trauma

These patients are presented with exercise intolerance, altered vocalisation, stridor, respiratory distress, cyanosis and fainting, which are aggravated by excitement, hot conditions and very humid environments.

Examples

■ Lymphoma ■ Thymoma ■ Thyroid carcinoma ■ Progressive polyneuropathy in geriatric patients ■ Infection

Neuromuscular disease

■ Toxins (e.g. organophosphates) ■ Hypothyroidism ■ Immune-mediated disease ■ Endocrinopathies ■ Polymyopathy (e.g. myasthenia gravis)

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Larynx / Laryngeal paralysis Diagnosis The diagnosis is based on the patient’s medical history and clinical signs, physical and neurological examination, complete haematological and biochemical profiles, urinalysis, thoracic radiographs, evaluation of thyroid function and direct observation of the larynx.

The radiological study of the thorax rules out, among other intrathoracic lesions, aspiration pneumonia and a possible concomitant megaoesophagus.

Laryngeal ultrasound and transnasal laryngoscopy allow the evaluation of laryngeal motility without the need to sedate the patient, but have a lower success rate than an oral approach.

There are several anaesthetic protocols that minimally alter laryngeal motility to facilitate diagnosis. It is recommended to premedicate with acepromazine and butorphanol and to induce anaesthesia with small doses of propofol or alfaxalone.

Doxapram hydrochloride can be used to recover laryngeal motility in the event of anaesthesia-induced apnoea. The drug is administered in incremental doses (0.5 mg/kg; 1 mg/kg; 1.5 mg/kg) at 30-second intervals, during which the laryngeal motility is checked.

A diagnosis of laryngeal paralysis is confirmed if, after three doses of doxapram, normal movement of the larynx has not been restored.

Laryngoscopy is necessary to confirm the diagnosis of laryngeal paralysis.

Transoral laryngoscopy The direct observation of the movement of the larynx during breathing permits evaluation of the abduction and adduction of the arytenoid cartilages during inspiration and expiration, the opening of the glottis and the presence of concomitant lesions.

See video Laryngeal paralysis 1

There may be a paradoxical opening movement of the arytenoid cartilages as a result of outflowing air during expiration, which should not be confused with a normal abduction during inspiration.

See video Paradoxical movement

See video Laryngoscopy in a healthy patient

Laryngoscopy is performed with the patient under superficial anaesthesia. The objective is to be able to open the mouth without reducing laryngeal motility or causing apnoea (Fig. 1).

The ideal anaesthetic protocol is one that allows patient management, adequate jaw relaxation and maintenance of laryngeal reflexes with the least possible respiratory depression.

Medical treatment

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Conservative management of dogs with initial laryngeal paralysis aims to improve the patient’s quality of life through weight loss, stress reduction and exercise.

The most advanced cases of laryngeal paralysis require medical treatment focused on stabilising the patient’s respiratory function.

Other concurrent problems associated with airway obstruction such as hyperthermia, non-cardiogenic pulmonary oedema, aspiration pneumonia, etc. should be detected and treated.

The initial medical treatment is based on improving the patient’s oxygenation and reducing local inflammation of the larynx:

Fig. 1. Laryngoscopy of a patient with laryngeal paralysis will show that the arytenoid

cartilages are located in the central part of the larynx and do not separate during inspiration.

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Oxygen therapy using a mask or nasal oxygen cannulas without restraining the patient to avoid stress.

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Sedation with acepromazine (0.01-0.02 mg/kg IV), buprenorphine (0.0005-0.001 mg/kg IV) or butorphanol (0.1-0.25 mg/kg IV).

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Fast-acting glucocorticoids (dexamethasone: 0.1 mg/kg).

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Cooling in cases of hyperthermia.

■

If necessary, a temporary tracheostomy is made, but these patients are reported to have more complications after lateralisation of the arytenoids.

See General principles of neck surgery.

In the book Head and neck I

pages 2-4

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The head and neck II Arytenoid cartilage lateralisation Prevalence Technical difficulty

Surgery is indicated in patients with moderate to severe laryngeal paralysis. The objective is to expand the opening of the glottis without increasing the risk of aspirating food or liquids.

The most commonly used surgical technique is the lateralisation of the left arytenoid cartilage by suturing the muscular process of this cartilage to the cricoids. This intervention simulates the action of the dorsal cricoarytenoid muscle that rotates the arytenoid cartilage laterally.

Bilateral arytenoid cartilage lateralisation is recommended only in severe cases due to the risk of aspiration pneumonia.

Technique The patient is placed in right lateral recumbency with a pad under the neck to raise and rotate the neck so that the laryngeal area is exposed (Fig. 2).

130 Fig. 2. The laterorostral part of the neck is shaved

and disinfected and a pad or folded towel is placed underneath to extend the neck, while the head is rotated slightly to expose the laryngeal area. Jugular vein (blue arrow); maxillary vein (green arrow); linguofacial vein (orange arrow); skin incision (yellow line).

The skin is incised ventrally to the jugular vein, from the back of the jaw to 2 cm beyond the larynx, so that the incision runs dorsally to the larynx (Fig. 3).

Fig. 3. The larynx is approached on the left side,

ventral to the jugular vein, from the mandibular ramus to 1-2 cm caudally beyond the larynx.

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Larynx / Laryngeal paralysis

After incising the skin and platysma muscle, the sternocephalic muscle and dorsal jugular vein are dissected and retracted in a dorsal direction and the sternohyoid muscle ventrally to expose the larynx (Fig. 4).

Fig. 4. The sternohyoid muscles are dissected and

retracted ventrally and the sternocephalic muscle dorsally (this image shows the anatomical dissection in a cadaver).

The dorsal edge of the thyroid cartilage is palpated and the thyropharyngeal muscle is incised along the dorsomedial area 2 mm from the edge, to make suturing easier (Figs. 5 and 6).

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Fig. 5. The dorsal edge of the left thyroid cartilage

(white line) is palpated, where the thyropharyngeal muscle (blue arrow) is inserted.

a

b

Fig. 6. The thyropharyngeal muscle is incised approximately 1-2 mm from the edge of the thyroid cartilage through its medial side, to facilitate suturing.

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The head and neck II a A suture is placed on the thyroid cartilage to pull it laterally and expose the cricoarytenoid joint.

The cricoarytenoid muscle is identified, isolated and sectioned (Fig. 7) in order to access the cricoarytenoid joint (Fig. 8).

b

132

Fig. 7. The cricoarytenoid muscle (blue arrow) is

located, dissected and sectioned. The yellow arrow indicates the sectioned thyropharyngeal muscle.

Fig. 8. Incision and elevation of the cricoarytenoid

muscle (blue arrow) allows visualisation of the cricoarytenoid joint (white arrow). The yellow arrow indicates the sectioned thyropharyngeal muscle.

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